koordlet: revise cgroupRoot param in podsInformer

[saintube]

Ⅰ. Describe what this PR does

koordlet: revise podsInformer, pass cgroupRoot during the runtime instead of the global initialization.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 67.51%. Comparing base (a6159e4) to head (8dd6d05).
Report is 3 commits behind head on main.

Files	Patch %	Lines
pkg/koordlet/statesinformer/impl/states_pods.go	50.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1928      +/-   ##
==========================================
+ Coverage   67.49%   67.51%   +0.02%     
==========================================
  Files         416      416              
  Lines       46396    46397       +1     
==========================================
+ Hits        31313    31327      +14     
+ Misses      12797    12785      -12     
+ Partials     2286     2285       -1     

Flag	Coverage Δ
unittests	67.51% <50.00%> (+0.02%)	⬆️

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[zwzhang0107]

/lgtm
/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: zwzhang0107

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