Add a flag in QueryShardContext to differentiate inner hit query

[heemin32]

Description

Add a flag in QueryShardContext to differentiate inner hit query and normal query.

For k-NN nested fields, the query currently searches for the nested field document with the highest score for each parent document, returning only a single nested field document in the inner hit block. We want to modify this query behavior to retrieve all nested field documents in the inner hit block, rather than just the one with the highest score. To implement this, we need to identify whether the current query request is targeting an inner hit block or not.

Alternatives

• One alternatives is using stack trace to see if the query is made inside NestedInnerHitContextBuilder. This will increase query latency.
• Another alternative is making the k-NN nested query behavior to be same regardless it is for inner hit block or not. This will break backward compatibility because the score of parent doc will get changed from max to avg as we are returning multiple nested fields docs.

Related Issues

Resolves opensearch-project/k-NN#2249

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❌ Gradle check result for 11f7980: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for 7f16389: SUCCESS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.04%. Comparing base (e688388) to head (7f16389).
Report is 5 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #16600      +/-   ##
============================================
- Coverage     72.15%   72.04%   -0.11%     
+ Complexity    65128    65065      -63     
============================================
  Files          5315     5315              
  Lines        303573   303578       +5     
  Branches      43925    43925              
============================================
- Hits         219036   218707     -329     
- Misses        66565    66940     +375     
+ Partials      17972    17931      -41     

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[msfroh]

Thanks, @heemin32. This makes sense!