pkg/otlp: Add instrumentation_scope_metadata_as_tags

[keisku]

What does this PR do?

Add a new flag named instrumentation_scope_metadata_as_tags to deprecate the current flag, instrumentation_library_metadata_as_tags.

Motivation

Since https://github.com/open-telemetry/opentelemetry-proto/releases/tag/v0.15.0, InstrumentationLibrary had been deprecated and open-telemetry/opentelemetry-collector#5219 removed it eventually.

This is confusing since the rest of the project has moved to the new name, so we should introduce a new flag that uses the instrumentation scope name, and deprecate the current one.

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

Reviewer's Checklist

• If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• Use the major_change label if your change either has a major impact on the code base, is impacting multiple teams or is changing important well-established internals of the Agent. This label will be use during QA to make sure each team pay extra attention to the changed behavior. For any customer facing change use a releasenote.
• A release note has been added or the changelog/no-changelog label has been applied.
• Changed code has automated tests for its functionality.
• Adequate QA/testing plan information is provided if the qa/skip-qa label is not applied.
• At least one team/.. label has been applied, indicating the team(s) that should QA this change.
• If applicable, docs team has been notified or an issue has been opened on the documentation repo.
• If applicable, the need-change/operator and need-change/helm labels have been applied.
• If applicable, the config template has been updated.

[sgnn7]

LGTM for agent-core owned files (config template)

[cswatt]

leaving a tiny edit, approving so as not to block on it