[BUG] enable-partial-results set to "no" does not return error during cluster partition

[talxsha]

Describe the bug
When setting enable-partial-results to no, running queries during cluster partition returns some results instead of generating an error.

To Reproduce

1. Start a CME cluster with 2+ shards
2. Create an index and ingest some vectors
3. Set enable-partial-results to no
4. Cause cluster partition where some shards are still OK and some are not
5. Run a query on one of the "good" shards

Expected behavior
Running the steps above will return some results, but this scenario should generate an error.

Related issues

1. Incomplete TIMEOUT and blocked-client handling can result in DOS #167
2. Query Timeouts Need to be able to return partial results. #201

[allenss-amazon]

I wrote some simple tests, and I found that the case you are pointing at seems to work. However it did identify failure modes when enable-partial-results is set to 'yes'. I believe these failures only happen in a shard-down situation -- not in a long-running timeout situation. If my belief is correct, I think we can live with it for a while (i.e. not a GA blocker).

I pushed my test case as a draft PR. #361 Somebody can use this to investigate what's going on and hopefully to fix it.