Allow non-reserved-keywords for index names

[GuptaManan100]

Description

This PR fixes the issue described in #15589. Vitess wasn't allowing non-reserved keywords for index names. MySQL however accepts this syntax. This PR fixes this issue by patching the parser.

Related Issue(s)

• Fixes Bug Report: Parser issue #15589

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.06%. Comparing base (b2e5ce7) to head (47da54e).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15602      +/-   ##
==========================================
+ Coverage   65.78%   68.06%   +2.28%     
==========================================
  Files        1561     1561              
  Lines      194901   195288     +387     
==========================================
+ Hits       128209   132930    +4721     
+ Misses      66692    62358    -4334     

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