[installer]: remove the custom labels from the selector labels

[mrsimonemms]

Description

Remove a limitation on the custom labels by removing the customisation on the selector labels. These are "reverted" to just using the default labels function instead so they're consistent.

Related Issue(s)

Fixes #11952

How to test

Deploy via KOTS.

1. Use a default configuration
2. Upload a configuration as per the docs:

customization:
  - apiVersion: "*"
    kind: "*"
    metadata:
      name: "*"
      labels:
        hello: world
      annotations:
        hello: world

3. Redeploy with the default configuration

All of these should install fine.

Release Notes

[installer]: remove the custom labels from the selector labels

Documentation

Werft options:

• /werft with-preview

[mrsimonemms]

This is blocked by Go formatting issues, which is being fixed in #11958

[cooperbenson-qz]

Awesome, thanks for making this change!

[corneliusludmann]

Change looks good to me.

Would be a good opportunity to add a test (basically a *.golden file with the result of the config you added in the PR description). What do you think?

/hold in case you want to add this

[mrsimonemms]

@corneliusludmann a very good idea, I'll do that

[mrsimonemms]

/unhold