fix ClassCastException when finalize hyperUnique metric in sql

[kaijianding]

Description

for a sql like this

select count(1) as totalData
from  (
   select count(distinct unique_user_id) as uv
   from a_table
   group by city_name
   order by uv
) t

unique_user_id is hyperUnique metric.

java.lang.ClassCastException is thrown as

java.lang.Long cannot be cast to java.lang.Double

The reason is that count(distinct unique_user_id) is Long in row signature, but the comparator in HyperUniqueFinalizingPostAggregator is Double

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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, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

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Key changed/added classes in this PR

• HyperUniqueFinalizingPostAggregator

[kaijianding]

The CI failure java.lang.AssertionError: expected [200 OK] but found [401 Unauthorized] in 30393.61 (Compile=openjdk8, Run=openjdk8, ZK=3.4) leadership and high availability integration tests should be unrelated

[clintropolis]

Change looks good to me, any chance you can add a test that covers this case?

[vivek-kandhvar]

Is this merged or just deleted?