[VTAdmin] Insert into schema cache if exists already and not expired

[notfelineit]

Description

This PR modifies vtadmin-web's schema cache Add method, such that if the key already exists, and is not expired yet, we Replace the record instead of calling Add. Add will always fail if there is an existing record that is not expired yet.

This will be backported to v21, as it is affecting users at least this far back.

Related Issue(s)

#17906

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 Added
• Did the new or modified tests pass consistently locally and on CI? Yes
• Documentation was added or is not required N/A

Deployment Notes

None

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 67.53%. Comparing base (96f4535) to head (2fe4ad3).
Report is 19 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtadmin/cache/cache.go	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17908      +/-   ##
==========================================
+ Coverage   67.47%   67.53%   +0.05%     
==========================================
  Files        1594     1597       +3     
  Lines      259064   259822     +758     
==========================================
+ Hits       174804   175471     +667     
- Misses      84260    84351      +91     

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[frouioui]

is it not the same thing we do from line 41 to 47?

[deepthi]

this is just adding an echo so that we can see how far the script got, and where it might be stuck, if at all.

[notfelineit]

Yes Deepthi is correct - just a sanity check that vtctld client was initiated, and we're moving onto curling now! 😄