Remove squash on `configtls.TLSClientSetting` in contrib

[Aneurysm9]

Describe the issue

Based on this PR (open-telemetry/opentelemetry-collector#4063) in collector repo, configtls.TLSClientSetting should be defined as mapstructure: "tls,omitempty".

Below links are files where changes are needed:

• /internal/aws/proxy/cfg.go
• /extension/awsxrayproxy/config.go
• /exporter/elasticexporter/config.go
• /exporter/observiqexporter/config.go
• /exporter/splunkhecexporter/config.go
• /exporter/splunkhecexporter/config.go

[hyunuk]

@Aneurysm9 , please assign me this issue!