Add Advance Post Filter Integ Tests Scenarios

[vibrantvarun]

Description

This PR contains following

1. Adding Post Filter Advance integ tests
2. Segregating all Util class in textFixtures to increase reusability

Issue

#640

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

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.

[vibrantvarun]

BWC tests are failing because of #688

[vibrantvarun]

BWC tests are failing because of opensearch-project/ml-commons#2333

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.42%. Comparing base (cc6a6b2) to head (27cc05d).
Report is 10 commits behind head on main.

❗ Current head 27cc05d differs from pull request most recent head 64e9d46. Consider uploading reports for the commit 64e9d46 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #694      +/-   ##
============================================
+ Coverage     84.04%   84.42%   +0.37%     
- Complexity      744      750       +6     
============================================
  Files            59       59              
  Lines          2313     2324      +11     
  Branches        374      375       +1     
============================================
+ Hits           1944     1962      +18     
+ Misses          214      213       -1     
+ Partials        155      149       -6     

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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-694-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 86f6d4c62d02e953aa31d5d7a5b9716b93a3d8a2
# Push it to GitHub
git push --set-upstream origin backport/backport-694-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-694-to-2.x.

[junqiu-lei]

@vibrantvarun Can you do a manual backport PR to 2.x? Since this code change is causing other 2.x backport PR CI failure.

[vibrantvarun]

Waiting for ml-commons PR to get merged