fix: use custom k8s label to inject certificates where needed

[mowies]

This PR

• fixes the helm chart by removing duplicate part-of labels
• adds a new custom label that is used to inject certificates into k8s resources through certificate-operator
• makes the new custom label configurable through the helm values
• makes already existing k8s part-of labels consistent

Fixes #1287

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[codecov]

Codecov Report

Merging #1288 (db65453) into main (b5f4e91) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1288   +/-   ##
=======================================
  Coverage   59.83%   59.83%           
=======================================
  Files         138      138           
  Lines       10462    10462           
=======================================
  Hits         6260     6260           
  Misses       3967     3967           
  Partials      235      235           

Flag	Coverage Δ
certificate-operator	64.15% <ø> (ø)
component-tests	60.45% <ø> (ø)
lifecycle-operator	78.34% <ø> (ø)
metrics-operator	77.80% <ø> (ø)
scheduler	21.75% <ø> (ø)

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication