add sampling rate for theta sketch

[natsumehu]

Fixes #8714.

Description

When dealing with highly partitioned/fragmented data, thetasketch module spent most of the time merging the sketches. It would also increase the size of the segments. We want to use the p sampling config of the sketch module to make it better. Setting the sampling to, say, p = 0.5, for all sketches, will automatically throw out 50% of all the data coming in to all the sketches. This would also potentially reduce the query time by sacrificing some accuracy.

We change the theta sketch module, just add another parameter of the constructor and use it to the merger.

Fixed the bug ...

Renamed the class ...

Added a forbidden-apis entry ...

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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.
• 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.
• added integration tests.
• been tested in a test Druid cluster.

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Key changed/added classes in this PR

• SketchAggregatorFactory

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