Update receiverhelper for requests that failed to be received

[gizas]

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Description

This is an ongoing work to add :

• In the endOp function of ObsReport, errors are classified as either:
  • Downstream errors (refused) - when internal.IsDownstreamError(err) returns true
  • Internal errors - when the error is not a downstream error
• New metrics otelcol_receiver_internal_errors_spans, otelcol_receiver_internal_errors_metric_points and otelcol_receiver_internal_errors_log_records in case of inetrnal errors returned above
• Support in OTLP receiver to handle IsClientDisconnectError. Network disconnect errors will be reported in otelcol_receiver_internal_errors_metric_points
• Support of otelcol_receiver_requests metric that will determines the outcome of the request:
  • "success" if there's no error
  • "refused" if there's a downstream error
  • "failure" if there's an internal error

Link to tracking issue

Fixes # https://github.com/open-telemetry/opentelemetry-collector/issues/12207

Testing

Only added the integration tests. That is why opened this is as a draft

Documentation

See updated receiver/receiverhelper/documentation.md