feat: add constant for k8s max name length

[Diaphteiros]

What this PR does / why we need it:
Adds a constant for the maximum k8s name length. This is useful for the shorten function. Also adds a shorten function that does not return an error, but panics instead.

Which issue(s) this PR fixes:
None

Special notes for your reviewer:

Release note:

The `pkg/controller` package now has a constant `K8sMaxNameLength` that holds the maximum length for k8s resource names. This is useful in combination with the package's `ShortenToXCharacters` function.

In addition to the `pkg/controller` package's `ShortenToXCharacters` function, there is now also a `ShortenToXCharactersUnsafe` function which panics instead of returning an error if something goes wrong.