Uniform defaults for `exporterhelper`

[mx-psi]

The exporterhelper package provides certain reusable helpers for common needs like queueing, retrying with backoff or timeouts. As of e23c9d0 the timeout setting is enabled by default but the rest are not:

opentelemetry-collector/exporter/exporterhelper/common.go

Lines 102 to 108 in e23c9d0

	opts := &baseSettings{
	TimeoutSettings: DefaultTimeoutSettings(),
	// TODO: Enable queuing by default (call DefaultQueueSettings)
	QueueSettings: QueueSettings{Enabled: false},
	// TODO: Enable retry by default (call DefaultRetrySettings)
	RetrySettings: RetrySettings{Enabled: false},
	}

This issue is to address the TODOs in the code. The current status is a bit confusing, since the documentation does not state which settings are enabled by default and which are not.

The individual items are to

• decide if timeout capabilities should be enabled by default and document if so,
• decide if queue capabilities should be enabled by default and document if so and
• decide if retry capabilities should be enabled by default and document if so.

I think timeout and queueing are safe to enable by default, while retries are a bit more doubtful: some of the exporters in contrib do several network requests per ConsumeTraces/Metrics/Logs call, so in situations of partial success (e.g. 1st request passes and the 2nd fails), it may not be safe or desirable to re-do previous requests. It may be fine to enable retries with a caveat on partial success situations.

[dmitryax]

This should wait for #6767 and #8122 to be resolved first

[mx-psi]

@dmitryax Is it time to look into this or should we still wait?