CNDB-12437: BigTableScanner should throw an IllegalStateException if the next row iterator is requested without consuming the previous

[jkni]

What is the issue

SSTableScannerTest tests for scanners throwing an IllegalStateException in this scenario fails for bigtable.

What does this PR fix and why was it fixed

This PR adds the same check for BigTableScanner as TrieIndexScanner already had. Improved test coverage exposed this as a genuine defect; BigTableScanner should contain this check, and its absence was an error.

Checklist before you submit for review

• 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

[jkni]

This patch was recommended by Branimir. I agree that its absence was an error.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
58.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

✔️ Build ds-cassandra-pr-gate/PR-1511 approved by Butler

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Approved by Butler
See build details here