Adding Reciprocal Rank Fusion (RRF) in hybrid query

[ryanbogan]

Description

Merges the feature branch for Reciprocal Rank Fusion (RRF) now that we have App Sec sign-off

Contains changes from the following PR's:

• Reciprocal Rank Fusion (RRF) normalization technique in hybrid query #874
• Add integration and unit tests for missing RRF coverage #997
• Integrate explainability for hybrid query into RRF processor #1037

Related Issues

#659

Check List

• New functionality includes testing.
• New functionality has been documented.
• [] API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[yuye-aws]

@ryanbogan Can you resolve the conflicting files?

[yuye-aws]

@martin-gaievski I remember there was a PR towards the feature branch. Do you know how to compare these two PRs?

[martin-gaievski]

@martin-gaievski I remember there was a PR towards the feature branch. Do you know how to compare these two PRs?

while feature is in development we merge every PR to feature branch. Once we're code complete and other things like app sec are done we merge everything from feature branch to main. This PR is exactly that, @ryanbogan has listed all previously merged to feature branch PRs in the description

[codecov]

Codecov Report

Attention: Patch coverage is 87.66234% with 19 lines in your changes missing coverage. Please review.

Project coverage is 80.51%. Comparing base (b084838) to head (312c7f7).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...rocessor/normalization/ScoreNormalizationUtil.java	41.17%	6 Missing and 4 partials ⚠️
...pensearch/neuralsearch/processor/RRFProcessor.java	84.21%	0 Missing and 6 partials ⚠️
...rmalization/MinMaxScoreNormalizationTechnique.java	60.00%	2 Missing ⚠️
...essor/normalization/RRFNormalizationTechnique.java	97.72%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1086      +/-   ##
============================================
+ Coverage     80.38%   80.51%   +0.12%     
- Complexity     1157     1211      +54     
============================================
  Files            87       93       +6     
  Lines          4018     4141     +123     
  Branches        682      697      +15     
============================================
+ Hits           3230     3334     +104     
- Misses          533      540       +7     
- Partials        255      267      +12     

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.x 2.x
# Navigate to the new working tree
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-1086-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 f6d8a12de3dca307b8f2638bbeb6fcd930ee304e
# Push it to GitHub
git push --set-upstream origin backport/backport-1086-to-2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-1086-to-2.x.