CNDB-16203: Make the counters in QueryContext plain longs (#2153)

[driftx]

We don't need all the counters in QueryContext to be LongAdder, since they are only accessed by the query's thread.

They used to be plain longs until VECTOR-SEARCH-29 parallelized vector searches, making them accessed by multiple threads. However, that parallelization was removed by the BM25 patch.

The system properties USE_PARALLEL_INDEX_READ and PARALLEL_INDEX_READ_NUM_THREADS are removed, since they were no-op since the introduction of BM25. Since we don't reject unknown system properties, they will remain no-op.

[github-actions]

Checklist before you submit for review

• This PR adheres to the Definition of Done
• Make sure there is a PR in the CNDB project updating the Converged Cassandra version
• Use NoSpamLogger for log lines that may appear frequently in the logs
• Verify test results on Butler
• Test coverage for new/modified code is > 80%
• Proper code formatting
• Proper title for each commit staring with the project-issue number, like CNDB-1234
• Each commit has a meaningful description
• Each commit is not very long and contains related changes
• Renames, moves and reformatting are in distinct commits
• All new files should contain the DataStax copyright header instead of the Apache License one

[driftx]

Nothing substantial, minor CassandraRelevantProperties changes.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
94.6% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

❌ Build ds-cassandra-pr-gate/PR-2326 rejected by Butler

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3 regressions found
See build details here

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Found 3 new test failures

Test	Explanation	Runs	Upstream
o.a.c.concurrent.StageTimeMeasurementTest.executionAndQueueTimeAreCountedOnSubmitWithResult (compression)	REGRESSION	🔴	0 / 30
o.a.c.index.sai.cql.VectorCompaction100dTest.testOneToManyCompaction[dc true] ()	NEW	🔴	0 / 30
o.a.c.index.sai.cql.VectorSiftSmallTest.testSiftSmall[dc false] ()	NEW	🔴	0 / 30

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Found 1 known test failures

[djatnieks]

note: the StageTimeMeasurementTest failures in CI also fail locally for me on main-5.0