fix: route engine to handle column truncation for execute after lookup

[harshit-gangal]

Description

This PR fixes the bug with route with lookup vindex where Vindex Lookup operator on calling the Route was not truncating the output.
This was missed for non-streaming execution mode.

Backport Reason: This is correctness issue with the query result output.

Related Issue(s)

• Fixes Bug Report: Vitess returns rows with wrong columns #16965

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]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.34%. Comparing base (da49d08) to head (3be9bab).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16981      +/-   ##
==========================================
- Coverage   69.35%   69.34%   -0.01%     
==========================================
  Files        1571     1571              
  Lines      204183   204180       -3     
==========================================
- Hits       141601   141596       -5     
- Misses      62582    62584       +2     

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[arthurschreiber]

Sweet! Thanks for looking into this! 🙇‍♂️