fix(installer): Revert immutable k8s labels

[mowies]

This PR

• reverts some changes from feat(installer): Helm Chart revamp #7678 since they broke the keptn installation
• renames all helper functions to be prefixed with keptn.* to prevent naming collisions with bitnami's common chart which is used in mongodb
• speeds up the ZD test pipeline slightly by only installing the node dependencies if the cypress tests are run alongside the go tests

Fixes #8209
Integration test run: https://github.com/keptn/keptn/actions/runs/2581393075

[codecov]

Codecov Report

Merging #8213 (0ef7903) into master (3ee5d1b) will increase coverage by 0.00%.
The diff coverage is 16.66%.

@@           Coverage Diff           @@
##           master    #8213   +/-   ##
=======================================
  Coverage   62.93%   62.94%           
=======================================
  Files         628      628           
  Lines       33647    33647           
  Branches     1658     1658           
=======================================
+ Hits        21176    21179    +3     
+ Misses      11172    11169    -3     
  Partials     1299     1299           

Impacted Files	Coverage Δ
distributor/pkg/config/envconfig.go	54.88% <0.00%> (ø)
mongodb-datastore/handlers/events.go	0.00% <0.00%> (ø)
...stributor/pkg/uniform/controlplane/controlplane.go	97.64% <100.00%> (ø)
cli/pkg/config/cli_config.go	59.75% <0.00%> (+3.65%)	⬆️

Flag	Coverage Δ
approval-service	64.61% <ø> (ø)
distributor	69.88% <20.00%> (ø)
helm-service	47.57% <ø> (ø)
jmeter-service	25.29% <ø> (ø)
lighthouse-service	75.07% <ø> (ø)
mongodb-datastore	57.94% <0.00%> (ø)

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.7% Duplication