CompactionTask throws exception on conflicting segmentGranularity

[suneet-s]

Description

A follow up to #10843

Since there are 2 ways for a user to specify segmentGranularity - this change makes throws an exception if a user accidentally submits a compaction task with conflicting segmentGranularities - by using the old way and the new way at the same time.

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This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• 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.

[suneet-s]

I couldn't decide what it means to have a granularitySpec.getSegmentGranularity() be null and segmentGranularity be non null, so I figured it would be good to flag that as a conflict as well

[suneet-s]

• No integration tests added since this is fully covered by the unit tests and it's a test of edge cases.
• No documentation added because this would conflict with First refactor of compaction docs #10935 which is already in flight