Revert "CNDB-16243: Improve ChunkCache Key in order to keep O(1) access time (#2156)"

[pkolaczk]

This reverts commit 7c75761.

[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

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
87.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

❌ Build ds-cassandra-pr-gate/PR-2320 rejected by Butler

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4 regressions found
See build details here

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Found 4 new test failures

Test	Explanation	Runs	Upstream
o.a.c.index.sai.cql.VectorCompaction100dTest.testOneToManyCompactionTooManyHoles[version=ec enableNVQ=false]	REGRESSION	🔴	0 / 30
o.a.c.index.sai.cql.VectorSiftSmallTest.testMultiSegmentBuild[version=fa enableNVQ=false enableFused=false]	REGRESSION	🔴	0 / 30
o.a.c.index.sai.cql.VectorTypeTest.testTwoPredicates[version=ca enableNVQ=false enableFused=false]	REGRESSION	🔴	0 / 30
o.a.c.index.sai.memory.VectorMemtableIndexTest.randomQueryTest (compression)	REGRESSION	🔴	0 / 30

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Found 4 known test failures

[pkolaczk]

Test failures unrelated. This revert has already been tested in April 2026 release.