[chore] [exporter/clickhouseexporter] full refactor for ClickHouse component (#40536)

#### Description

This PR intends to reorganize the code of the exporter without making
any user-facing changes to the behavior or config. The goal is to make
it more maintainable and revise all previous changes into one cohesive
component.

Apologies in advance for the many changes, but I wanted this to be
runnable so we can merge it into main. **Let me know if we need to split
anything out, or make any changes.**

Notable changes:
- All `clickhouse-go` database calls now use the library's native Go
interface instead of the `database/sql` interface. This is more
efficient and easier to configure + test. There was a lot of overhead in
converting from `database/sql` to the driver's native structures, so
this has a performance benefit as well as more idiomatic code.
- Files have been reorganized so that code is in a more logical and easy
to find place. (For example, there were some shared functions inside the
`exporter_logs.go` file, even though it was unrelated to logs)
- SQL is no longer written inside the `.go` file, and is now using
`go:embed` to embed it from a directory of files.
- Moved generic code to the `internal` package to simplify the top level
package's exports.
- Optimized insert code for logs/traces to be more CPU efficient (there
were some redundant calls for converting attributes to `map`, wasting
CPU).

See testing section below for notes on test changes.

#### Testing

- Mocked database tests were replaced with full integration tests for
logs, traces, and metrics.
- Integration test share the same test container, ensuring quicker
testing (no more starting several containers for simple query tests)
- Preserved `goleak` checks for integration tests (and unit tests)
- Integration tests were split into multiple files (these are in
`*_integration_test.go` files)
- Unit tests are separate from the integration tests (these are in the
usual `_test.go` files)
- Added tests for new functions/cases
- Removed irrelevant/unhelpful tests

Author: SpencerTorres

exporter/clickhouseexporter/config.go

@@ -4,25 +4,25 @@
 package clickhouseexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/clickhouseexporter"
 
 import (
-	"database/sql"
 	"errors"
 	"fmt"
 	"net/url"
 	"time"
 
 	"github.com/ClickHouse/clickhouse-go/v2"
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configopaque"
 	"go.opentelemetry.io/collector/config/configretry"
 	"go.opentelemetry.io/collector/exporter/exporterhelper"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/clickhouseexporter/internal"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/clickhouseexporter/internal/metrics"
 )
 
 // Config defines configuration for clickhouse exporter.
 type Config struct {
 	// collectorVersion is the build version of the collector. This is overridden when an exporter is initialized.
 	collectorVersion string
-	driverName       string // for testing
 
 	TimeoutSettings           exporterhelper.TimeoutConfig `mapstructure:",squash"`
 	configretry.BackOffConfig `mapstructure:"retry_on_failure"`
@@ -68,15 +68,15 @@ type Config struct {
 
 type MetricTablesConfig struct {
 	// Gauge is the table name for gauge metric type. default is `otel_metrics_gauge`.
-	Gauge internal.MetricTypeConfig `mapstructure:"gauge"`
+	Gauge metrics.MetricTypeConfig `mapstructure:"gauge"`
 	// Sum is the table name for sum metric type. default is `otel_metrics_sum`.
-	Sum internal.MetricTypeConfig `mapstructure:"sum"`
+	Sum metrics.MetricTypeConfig `mapstructure:"sum"`
 	// Summary is the table name for summary metric type. default is `otel_metrics_summary`.
-	Summary internal.MetricTypeConfig `mapstructure:"summary"`
+	Summary metrics.MetricTypeConfig `mapstructure:"summary"`
 	// Histogram is the table name for histogram metric type. default is `otel_metrics_histogram`.
-	Histogram internal.MetricTypeConfig `mapstructure:"histogram"`
+	Histogram metrics.MetricTypeConfig `mapstructure:"histogram"`
 	// ExponentialHistogram is the table name for exponential histogram metric type. default is `otel_metrics_exponential_histogram`.
-	ExponentialHistogram internal.MetricTypeConfig `mapstructure:"exponential_histogram"`
+	ExponentialHistogram metrics.MetricTypeConfig `mapstructure:"exponential_histogram"`
 }
 
 // TableEngine defines the ENGINE string value when creating the table.
@@ -101,11 +101,36 @@ var (
 	errConfigInvalidEndpoint = errors.New("endpoint must be url format")
 )
 
+func createDefaultConfig() component.Config {
+	return &Config{
+		collectorVersion: "unknown",
+
+		TimeoutSettings:  exporterhelper.NewDefaultTimeoutConfig(),
+		QueueSettings:    exporterhelper.NewDefaultQueueConfig(),
+		BackOffConfig:    configretry.NewDefaultBackOffConfig(),
+		ConnectionParams: map[string]string{},
+		Database:         defaultDatabase,
+		LogsTableName:    "otel_logs",
+		TracesTableName:  "otel_traces",
+		TTL:              0,
+		CreateSchema:     true,
+		AsyncInsert:      true,
+		MetricsTables: MetricTablesConfig{
+			Gauge:                metrics.MetricTypeConfig{Name: defaultMetricTableName + defaultGaugeSuffix},
+			Sum:                  metrics.MetricTypeConfig{Name: defaultMetricTableName + defaultSumSuffix},
+			Summary:              metrics.MetricTypeConfig{Name: defaultMetricTableName + defaultSummarySuffix},
+			Histogram:            metrics.MetricTypeConfig{Name: defaultMetricTableName + defaultHistogramSuffix},
+			ExponentialHistogram: metrics.MetricTypeConfig{Name: defaultMetricTableName + defaultExpHistogramSuffix},
+		},
+	}
+}
+
 // Validate the ClickHouse server configuration.
 func (cfg *Config) Validate() (err error) {
 	if cfg.Endpoint == "" {
 		err = errors.Join(err, errConfigNoEndpoint)
 	}
+
 	dsn, e := cfg.buildDSN()
 	if e != nil {
 		err = errors.Join(err, e)
@@ -160,11 +185,6 @@ func (cfg *Config) buildDSN() (string, error) {
 	}
 	queryParams.Set("client_info_product", productInfo)
 
-	// Use database from config if not specified in path, or if config is not default.
-	if dsnURL.Path == "" || cfg.Database != defaultDatabase {
-		dsnURL.Path = cfg.Database
-	}
-
 	// Override username and password if specified in config.
 	if cfg.Username != "" {
 		dsnURL.User = url.UserPassword(cfg.Username, string(cfg.Password))
@@ -175,23 +195,6 @@ func (cfg *Config) buildDSN() (string, error) {
 	return dsnURL.String(), nil
 }
 
-func (cfg *Config) buildDB() (*sql.DB, error) {
-	dsn, err := cfg.buildDSN()
-	if err != nil {
-		return nil, err
-	}
-
-	// ClickHouse sql driver will read clickhouse settings from the DSN string.
-	// It also ensures defaults.
-	// See https://github.com/ClickHouse/clickhouse-go/blob/08b27884b899f587eb5c509769cd2bdf74a9e2a1/clickhouse_std.go#L189
-	conn, err := sql.Open(cfg.driverName, dsn)
-	if err != nil {
-		return nil, err
-	}
-
-	return conn, nil
-}
-
 // shouldCreateSchema returns true if the exporter should run the DDL for creating database/tables.
 func (cfg *Config) shouldCreateSchema() bool {
 	return cfg.CreateSchema
@@ -242,6 +245,32 @@ func (cfg *Config) tableEngineString() string {
 	return fmt.Sprintf("%s(%s)", engine, params)
 }
 
+// database returns the preferred database for creating tables and inserting data.
+// The config option takes precedence over the DSN's settings.
+// Falls back to default if neither are set.
+// Assumes config has passed Validate.
+func (cfg *Config) database() string {
+	if cfg.Database != "" && cfg.Database != defaultDatabase {
+		return cfg.Database
+	}
+
+	dsn, err := cfg.buildDSN()
+	if err != nil {
+		return ""
+	}
+
+	dsnDB, err := internal.DatabaseFromDSN(dsn)
+	if err != nil {
+		return ""
+	}
+
+	if dsnDB != "" && dsnDB != defaultDatabase {
+		return dsnDB
+	}
+
+	return defaultDatabase
+}
+
 // clusterString generates the ON CLUSTER string. Returns empty string if not set.
 func (cfg *Config) clusterString() string {
 	if cfg.ClusterName == "" {