Update the Supervisor endpoint to not restart the Supervisor if the spec was unmodified

[aho135]

Description

This PR adds an optional query parameter called restartIfUnmodified to the /druid/indexer/v1/supervisor endpoint. The caller can optionally set restartIfUnmodified=false so that the supervisor is not restarted if the spec is unchanged. Multiple members of the community mentioned that they maintain their own scripts to check whether the spec has changed before submitting to the endpoint: https://apachedruidworkspace.slack.com/archives/C0303FDCZEZ/p1738017586080509

For those that rely on this endpoint for restarting the supervisor, the behavior remains unchanged as restartIfUnmodified defaults to true.

Release note

Adds an optional query parameter called restartIfUnmodified to the /druid/indexer/v1/supervisor endpoint. Callers can set restartIfUnmodified=false to not restart the supervisor if the spec is unchanged. Example:

curl -X POST --header "Content-Type: application/json" -d @supervisor.json localhost:8888/druid/indexer/v1/supervisor?restartIfUnmodified=false

---

Key changed/added classes in this PR

• SupervisorResource
• SupervisorManager
• MetadataSupervisorManager
• SQLMetadataSupervisorManager
• SupervisorResourceTest

---

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.