koordlet: fix node memory collection

[saintube]

Ⅰ. Describe what this PR does

• Fix a bug of the metrics advisor in which the node memory usage in NodeMetric shows as kilo-bytes while the other fields use bytes.
• Add UTs for node resource collector to avoid regression.
• Revise logs and error handling in the states informer.

Ⅱ. Does this pull request fix one issue?

Fixed the bug in koordlet's node resource collector (introduced in #1316).

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

[saintube]

/cc @zwzhang0107 @jasonliu747 @LambdaHJ

[codecov]

Codecov Report

Patch coverage: 43.63% and project coverage change: -0.02 ⚠️

Comparison is base (f833fd9) 64.50% compared to head (bcad6b8) 64.49%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1392      +/-   ##
==========================================
- Coverage   64.50%   64.49%   -0.02%     
==========================================
  Files         330      331       +1     
  Lines       33905    33990      +85     
==========================================
+ Hits        21872    21921      +49     
- Misses      10427    10460      +33     
- Partials     1606     1609       +3     

Flag	Coverage Δ
unittests	64.49% <43.63%> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
pkg/koordlet/statesinformer/states_pods.go	60.10% <0.00%> (-1.56%)	⬇️
pkg/koordlet/statesinformer/states_nodemetric.go	53.36% <40.00%> (-0.35%)	⬇️
...collectors/noderesource/node_resource_collector.go	64.55% <80.00%> (ø)

... and 1 file with indirect coverage changes

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[LambdaHJ]

/lgtm

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes, jasonliu747

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• pkg/koordlet/OWNERS [hormes,jasonliu747]

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[hormes]

/lgtm