[DBMON-6221] Add otel metric mapping support to Postgres OOTB dashboards

[eric-weaver]

What does this PR do?

Adds semantic_mode support to Postgres OOTB dashboards so that Otel postgres native metrics can be automatically mapped to Datadog's postgres integration dashboards

Note: there are a couple of metric widgets that still won't currently work due to not currently having an equivalent metric on the Otel side

Example of an otel collector configured to emit postgres metrics showing on the dashboard

Motivation

https://datadoghq.atlassian.net/browse/DBMON-6219

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[github-actions]

⚠️ Recommendation: Add qa/skip-qa label

This PR does not modify any files shipped with the agent.

To help streamline the release process, please consider adding the qa/skip-qa label if these changes do not require QA testing.