Improves Rest Layer Authz robustness

[DarshitChanpura]

Description

This PR improves the robustness of the path check when evaluating whether the path supports rest layer authorization.

• Category : Enhancement

• What is the old behavior before changes and new behavior after changes?
  The request will not be evaluated at REST layer if they were missing leading or trailing slashes since restPathMatches() function will filter them out. Post this fix the leading/trailing slashes will not determine whether the path matches, but the actual path will.

Testing

• automated tests

Check List

• New functionality includes testing
  - [ ] New functionality has been documented
  - [ ] New Roles/Permissions have a corresponding security dashboards plugin PR
  - [ ] API changes companion pull request created
• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.89%. Comparing base (1c898dc) to head (6108c30).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4879      +/-   ##
==========================================
- Coverage   69.90%   69.89%   -0.01%     
==========================================
  Files         320      320              
  Lines       21688    21690       +2     
  Branches     3460     3461       +1     
==========================================
+ Hits        15160    15161       +1     
- Misses       4734     4736       +2     
+ Partials     1794     1793       -1     

Files with missing lines	Coverage Δ
...opensearch/security/filter/SecurityRestFilter.java	84.44% <100.00%> (+0.23%)	⬆️

... and 4 files with indirect coverage changes