Update OpenSearch Version for 2.12.0 including recent auth changes

[YANG-DB]

Changes

Add OTEL-Col support for Opensearch exporter update auth details for opensearch exporter in the OTEL collector update O/S dashboard to 2.12 GA version

Merge Requirements

For new features contributions please make sure you have completed the following essential items:

• [ ] CHANGELOG.md updated to document new feature additions
• [ ] Appropriate documentation updates in the docs
• [ ] Appropriate Helm chart updates in the helm-charts

Maintainers will not merge until the above have been completed. If you're unsure which docs need to be changed ping the @open-telemetry/demo-approvers.

[github-actions[bot]]

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