[Backport-2.x] Removed unused extension directory

[owaiskazi19]

Description

Backport of #8674

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/20164/
• CommitID: 657fcae

[codecov]

Codecov Report

Merging #8690 (657fcae) into 2.x (90d1da2) will decrease coverage by 0.02%.
The diff coverage is 67.34%.

@@             Coverage Diff              @@
##                2.x    #8690      +/-   ##
============================================
- Coverage     70.61%   70.59%   -0.02%     
- Complexity    57254    57297      +43     
============================================
  Files          4756     4757       +1     
  Lines        271489   271521      +32     
  Branches      40019    40025       +6     
============================================
- Hits         191710   191691      -19     
- Misses        63340    63379      +39     
- Partials      16439    16451      +12     

Impacted Files	Coverage Δ
...nsearch/search/internal/FilteredSearchContext.java	8.92% <0.00%> (-0.25%)	⬇️
...arch/aggregations/DefaultAggregationProcessor.java	13.95% <50.00%> (+1.75%)	⬆️
.../search/aggregations/BucketCollectorProcessor.java	65.62% <65.62%> (ø)
.../org/opensearch/search/internal/SearchContext.java	38.00% <66.66%> (+1.82%)	⬆️
...va/org/opensearch/search/DefaultSearchContext.java	78.90% <100.00%> (+0.33%)	⬆️
...arch/aggregations/AggregationCollectorManager.java	83.33% <100.00%> (+10.00%)	⬆️
...h/aggregations/ConcurrentAggregationProcessor.java	81.25% <100.00%> (+1.25%)	⬆️
...ensearch/search/internal/ContextIndexSearcher.java	68.23% <100.00%> (+0.18%)	⬆️

... and 444 files with indirect coverage changes