Improve error logging for OTLP gRPC exporter

[dashpole]

Is your feature request related to a problem?

I used the gRPC exporter, and it failed to export to my backend (this was my fault). I got the following error, even when debug logging was enabled:

ERROR:opentelemetry.exporter.otlp.proto.grpc.exporter:Failed to export metrics to <endpoint>, error code: StatusCode.INVALID_ARGUMENT

It looks like the error message is not being logged here:

opentelemetry-python/exporter/opentelemetry-exporter-otlp-proto-grpc/src/opentelemetry/exporter/otlp/proto/grpc/exporter.py

Lines 341 to 347 in 58f2d16

	logger.error(
	"Failed to export %s to %s, error code: %s",
	self._exporting,
	self._endpoint,
	error.code(),
	exc_info=error.code() == StatusCode.UNKNOWN,
	)

Describe the solution you'd like

I would like to log the error's details.

Describe alternatives you've considered

No response

Additional Context

This may also apply to the trace or log grpc exporter. I haven't checked

Would you like to implement a fix?

No

[dashpole]

cc @aabmass