opentelemetry: fix support for schema_url in opentelemetry plugins (backport of #10201).

[pwhelan]

Summary

Add support for scope_logs.schema_url for opentelemetry. This is a backport of #10201 to the 3.2 series.

Description

Encode scope_logs.schema_url inside scope for in_opentelemetry and then set it again in out_opentelemetry using a record accessor that searches for scope.schema_url inside the logs group attributes.

This should fix issue #10143 for the 3.2 series.

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Testing
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Documentation

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Backporting

• Backport to latest stable release.

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