[PROTOTYPE] [PERF] SPANN incorrectly acquires write lock for hnsw

[HammadB]

this is a prototype, putting it up for sharing

[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[blacksmith-sh]

Found 3 test failures on Blacksmith runners:

Failures

Test	View Logs
chroma-index/ spann::types::tests::test_long_running_data_integrity_multiple_parallel_runs_with_updat es_deletes	View Logs
chroma-index/spann::types::tests::test_long_running_data_integrity_parallel	View Logs
garbage_collector/ garbage_collector_component::tests::test_k8s_integration_gc_v2_and_database_hard_delete	View Logs