Reduce metadata IO during segment allocation

[kfaraz]

Revives #17420

Description

The changes here try to reduce metadata IO during segment allocation by fetching segment payloads
for only the required segments. For other segments, only fetching the segment ID suffices.

Changes

• Add Overlord runtime property druid.indexer.tasklock.batchAllocationReduceMetadataIO.
• Setting this flag to true allows the Overlord to fetch only necessary segment payloads during segment allocation

Release note

• Add Overlord runtime property druid.indexer.tasklock.batchAllocationReduceMetadataIO.
• Setting this flag to true allows the Overlord to fetch only necessary segment payloads during segment allocation

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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]

Should this be always on and then we remove this config in next release ?

[kfaraz]

Yeah, I guess the changes are safe enough. We can always keep it on. Let me try to run ITs with it turned on.