koordlet: record invoke metrics for runtime hook

[saintube]

Ⅰ. Describe what this PR does

koordlet: add the following metrics to record the runtime hook's execution:

• koordlet_runtime_hook_invoked_duration_milliseconds
• koordlet_runtime_hook_reconciler_invoked_duration_milliseconds

Ⅱ. Does this pull request fix one issue?

Part of #1867.

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 67.44186% with 14 lines in your changes are missing coverage. Please review.

Project coverage is 67.54%. Comparing base (f3bc42a) to head (f4f1703).

Files	Patch %	Lines
pkg/koordlet/runtimehooks/reconciler/reconciler.go	55.55%	7 Missing and 1 partial ⚠️
pkg/koordlet/metrics/runtime_hook.go	75.00%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1961      +/-   ##
==========================================
+ Coverage   67.52%   67.54%   +0.02%     
==========================================
  Files         420      421       +1     
  Lines       47047    47084      +37     
==========================================
+ Hits        31767    31803      +36     
+ Misses      12968    12967       -1     
- Partials     2312     2314       +2     

Flag	Coverage Δ
unittests	67.54% <67.44%> (+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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• pkg/koordlet/OWNERS [zwzhang0107]

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