koordlet: fix GetAllPods error and wrong tsdb prometheus registry

[saintube]

Ⅰ. Describe what this PR does

koordlet:

1. Fix the outdated configured Prometheus registry for the TSDB.
2. Fix the panic when the kubeletStub GetAllPods/GetKubeletConfiguration returns a nil response.

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 81.81818% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 67.52%. Comparing base (3581c3d) to head (b87321d).

Files	Patch %	Lines
pkg/koordlet/metriccache/tsdb_storage.go	0.00%	1 Missing ⚠️
pkg/koordlet/statesinformer/impl/kubelet_stub.go	90.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1944   +/-   ##
=======================================
  Coverage   67.51%   67.52%           
=======================================
  Files         420      420           
  Lines       46954    46957    +3     
=======================================
+ Hits        31703    31707    +4     
+ Misses      12944    12939    -5     
- Partials     2307     2311    +4     

Flag	Coverage Δ
unittests	67.52% <81.81%> (+<0.01%)	⬆️

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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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