Change the log level from warning to debug to avoid noise when there …

[stonezdj]

…are many unused ldap groups for each user

fixes #20038

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Comprehensive Summary of your change

Issue being fixed

Fixes #(issue)

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• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
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• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 66.09%. Comparing base (c8c11b4) to head (126ba82).
Report is 295 commits behind head on main.

Files with missing lines	Patch %	Lines
src/core/auth/ldap/ldap.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #21034       +/-   ##
===========================================
+ Coverage   45.36%   66.09%   +20.72%     
===========================================
  Files         244     1049      +805     
  Lines       13333   114602   +101269     
  Branches     2719     2856      +137     
===========================================
+ Hits         6049    75749    +69700     
- Misses       6983    34711    +27728     
- Partials      301     4142     +3841     

Flag	Coverage Δ
unittests	66.09% <0.00%> (+20.72%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/core/auth/ldap/ldap.go	37.45% <0.00%> (ø)

... and 1287 files with indirect coverage changes

[chlins]

lgtm