CNDB-16344: SAI Rerankless ANN needs FP sim. score for coordinator's sort

[michaeljmarshall]

What is the issue

Fixes: https://github.com/riptano/cndb/issues/16344

What does this PR fix and why was it fixed

When ANN_USE_SYNTHETIC_SCORE is true, we send the score from the replica to the coordinator. We need that score to be the full precision score to ensure correct ordering. When a query supplies rerank_k: 0, the score is approximate though and can produce out of order results, as the test demonstrates. The fix is to configure the NodeQueueRowIdIterator appropriately to indicate when the score is in fact approximate. The FP score is only computed when ANN_USE_SYNTHETIC_SCORE is true.

[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
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

❌ Build ds-cassandra-pr-gate/PR-2184 rejected by Butler

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5 regressions found
See build details here

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Found 5 new test failures

Test	Explanation	Runs	Upstream
o.a.c.db.ColumnFamilyStoreTest.testDiscardSSTables	REGRESSION	🔴⚪	2 / 19
o.a.c.index.sai.cql.VectorCompaction100dTest.testOneToManyCompaction[dc false]	NEW	🔴⚪	0 / 19
o.a.c.index.sai.cql.VectorKeyRestrictedOnPartitionTest.partitionRestrictedTest[ca false] (compression)	REGRESSION	🔴🔵	0 / 19
o.a.c.index.sai.cql.VectorKeyRestrictedOnPartitionTest.partitionRestrictedWidePartitionBqCompressedTest[db false] (compression)	REGRESSION	🔴🔵	0 / 19
o.a.c.index.sai.cql.VectorSiftSmallTest.testRerankKZeroOrderMatchesFullPrecisionSimilarity[db false]	NEW	🔴⚪	0 / 19

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Found 2 known test failures