Cache segment metadata on the Overlord to speed up segment allocation and other task actions

[kfaraz]

NOT READY FOR REVIEW YET

Description

Design

Major changes

• Add Overlord runtime property druid.manager.segments.useCache (default value false)
• No change in flow when cache is disabled
• Add SqlSegmentsMetadataCache to poll committed and pending segments from the Overlord
• Add DatasourceSegmentsCache to cache committed and pending segments of a single datasource
• Add SegmentsMetadataTransaction to encapsulate all read/write operations performed within
  a transaction. This allows redirect all read/write operations within a transaction to either the cache
  or to the metadata store itself.
• Add SqlSegmentsMetadataTransactionFactory that creates either a SqlSegmentsMetadataTransaction
  or a SqlSegmentsMetadataCachedTransaction based on whether the cache is enabled and ready or not
• Use SegmentsMetadataTransaction to perform all operations in IndexerSQLMetadataStorageCoordinator

Testing

• Updated IndexerSQLMetadataStorageCoordinatorTest to run both with and without cache

Pending items

• Add UTs for the cache classes
• Wire up other existing UTs to use cache
• Update existing ITs to work with cache

Release note

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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.