Bug fix: fix postgres activity inflated query durations

[jmeunier28]

What does this PR do?

Adds a new column to activity queries for postgres, now, which is collected by calling the clock_timestamp() function. This will allow us to ingest the current time as seen by the database itself, and use that for our duration calculations for active queries in the backend.

Motivation

For the postgres integration, we're setting duration as payloadTimestamp - query_start, but payloadTimestamp is now() as calculated by the agent. It should instead be clock_timestamp() as reported by the database when the activity query is made.

This is likely adding 10-20 ms to our Postgres activity query durations.

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #11765 (f76a27a) into master (132d263) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Flag	Coverage Δ
postgres	91.83% <100.00%> (+0.16%)	⬆️

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