[DBM] [Postgres] Hides the query_activity.collection_interval option to prevent misuse

[aldrickdev]

What does this PR do?

This PR will just hid the query_activity.collection_interval option in the conf.yaml to prevent misuse.

Motivation

DBMON-5020

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.66%. Comparing base (8e8a37a) to head (3de5a37).
Report is 1 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
hive	?
hivemq	?
ignite	?
jboss_wildfly	?
kafka	?
postgres	93.25% <ø> (+18.29%)	⬆️
presto	?
solr	?

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