add detailed error message for grpc exporter

[weizhikuan]

Description

Fixes #4393

Small enhancement to expose detailed grpc error message to the log for the otel-grpc exporter.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Tested with follow tox envs:
py313-test-opentelemetry-exporter-otlp-proto-grpc-oldest
py313-test-opentelemetry-exporter-otlp-proto-grpc-latest
py314-test-opentelemetry-exporter-otlp-proto-grpc-oldest
py314-test-opentelemetry-exporter-otlp-proto-grpc-latest

All passed.

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[herin049]

We already have an open PR which addresses this: #5143