CNDB-15581: CDNB-15253: make UCS shard progression smoother when num_…

[michaelsembwever]

https://github.com/riptano/cndb/issues/15581

Port into main-5.0 commit 48eb797

CDNB-15253: make UCS shard progression smoother when num_shards and min sstable size are configured (https://github.com/datastax/cassandra/pull/2031)
### What is the issue

https://github.com/riptano/cndb/issues/15253 large shard count jump
was involved in HCD-130

### What does this PR fix and why was it fixed

Replace power-of-two shard progression with factorization-based smooth
growth when base shard count is not power of 2. This prevents
problematic large jumps. For example, with num_shards 1000 which is 5^3* 2^3:

- Before: 1 → 2 → 8 → 1000 (125x jump causes data loss due to hcd-130)
- After:  1 → 5 → 25 → 125 → 250 → 500 → 1000 (max 5x jump)

* new behavior can be disabled via
`-Dunified_compaction.use_factorization_shard_count_growth`

[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
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
97.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

❌ Build ds-cassandra-pr-gate/PR-2057 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.cql3.validation.operations.AggregationQueriesTest.testAggregationQueryShouldNotTimeoutWhenItExceedesReadTimeout (compression)	REGRESSION	🔴🔴	2 / 10
o.a.c.index.sai.cql.VectorBruteforceLocalTest.randomizedBqCompressedTest[ed] (compression)	REGRESSION	🔵🔴	0 / 10
o.a.c.nodes.NodesPersistenceTest.testUpdateTokens (compression)	REGRESSION	🔴🔵	0 / 10

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Found 6 known test failures