fix: [2.5] restore rbac empty meta panic

[shaoting-huang]

cp from master: #39141
related: #38985

[mergify]

@shaoting-huang go-sdk check failed, comment rerun go-sdk can trigger the job again.

[codecov]

Codecov Report

Attention: Patch coverage is 85.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 81.06%. Comparing base (95809ca) to head (4b7ca95).
Report is 8 commits behind head on 2.5.

Files with missing lines	Patch %	Lines
internal/metastore/kv/rootcoord/kv_catalog.go	82.35%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.5   #39143      +/-   ##
==========================================
+ Coverage   81.02%   81.06%   +0.03%     
==========================================
  Files        1389     1389              
  Lines      196343   196352       +9     
==========================================
+ Hits       159091   159170      +79     
+ Misses      31629    31580      -49     
+ Partials     5623     5602      -21     

Components	Coverage Δ
Client	78.26% <ø> (ø)
Core	69.55% <ø> (+<0.01%)	⬆️
Go	83.02% <85.00%> (+0.04%)	⬆️

Files with missing lines	Coverage Δ
internal/proxy/impl.go	83.86% <100.00%> (+<0.01%)	⬆️
internal/metastore/kv/rootcoord/kv_catalog.go	80.81% <82.35%> (ø)

... and 40 files with indirect coverage changes

[shaoting-huang]

rerun ut

[github-actions]

Hello shaoting-huang, you are not in the organization, so you do not have the permission to rerun the workflow, please contact @milvus-io/milvus-maintainers for help.

[shaoting-huang]

rerun ut

[tedxu]

/lgtm
/approve

[sre-ci-robot]

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