Adding metrics for custom resources

[cshiv]

PR contains following changes-

1. Configurations for scraping custom resource metrics related to Percona Kubernetes Operators
2. Configurations for scraping kubelet metrics.

[it-percona-cla]

All committers have signed the CLA.

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (23c95c7) 5.33% compared to head (8e160b7) 5.33%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
pkg/kubernetes/kubernetes.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main    #116      +/-   ##
========================================
- Coverage   5.33%   5.33%   -0.01%     
========================================
  Files         13      13              
  Lines       2850    2851       +1     
========================================
  Hits         152     152              
- Misses      2671    2672       +1     
  Partials      27      27              

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