Add JDBC transaction duration metrics

[trask]

Summary

• record stable db.client.operation.duration metrics for JDBC transaction spans

[Copilot]

Pull request overview

This PR enables recording of the stable db.client.operation.duration metric for JDBC transaction operations (e.g., COMMIT), aligning JDBC transaction instrumentation with the existing statement-level DB client metrics behavior.

Changes:

• Enabled DB client operation duration metrics on the JDBC transaction instrumenter.
• Added a regression test to assert db.client.operation.duration is emitted for a transaction (commit) with the expected attribute keys.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
instrumentation/jdbc/library/src/main/java/io/opentelemetry/instrumentation/jdbc/internal/JdbcInstrumenterFactory.java	Adds DbClientMetrics operation metrics to the transaction instrumenter so transaction spans contribute to db.client.operation.duration.
instrumentation/jdbc/library/src/test/java/io/opentelemetry/instrumentation/jdbc/datasource/JdbcTelemetryTest.java	Adds a test that exercises a transaction commit and asserts the stable DB client duration metric is emitted with expected attribute keys.