Fix flakiness in compaction ITs

[kfaraz]

Description

#17834 has made some ITs flaky due to a race condition in the /taskslots Coordinator API.
Since the Overlord now exposes APIs to update compaction configs, the Coordinator may have
a stale version of the config while trying to update the task slots. This config is refreshed from
the metadata store every minute. But if the config has just been updated on the Overlord and
the taskslots API is called, it may end up reverting the change performed by the Overlord API.

This issue does not exist with the other compaction config APIs.

Changes

• Use latest config in the /taskslots API

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This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[cryptoe]

While the Patch fixes the flakiness there is still a race in task slots update logic rite ? As in if we set the compaction config task slots via the overlord API, the coordinator API can override it no ?

[kfaraz]

Thanks for the review, @cryptoe !

[kfaraz]

While the Patch fixes the flakiness there is still a race in task slots update logic rite ? As in if we set the compaction config task slots via the overlord API, the coordinator API can override it no ?

Yes, but that is no different from the race condition between two users hitting the same API.