Fix VPA code generation

[voelzmo]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

Seems like code generation wasn't working for a while, as the dependency for hack/update-codegen.sh wasn't vendored. This script wasn't executed in a while, although there were changes in the API recently. This commit does a few things, separated into individual commits:

• introduce a new file hack/tools.go to pull in k8s.io/code-generator and have it correctly versioned in go.mod
• changing the commandline for generate-groups.sh from all to client,deepcopy,informer,lister. This excludes applyconfiguration, which we currently don't generate, but would be included in all
• actually run hack/update-codegen.sh to generate the deepcopy files and client-related files with the most recent API changes
• switch to kube-codegen.sh, as generate-groups.sh was showing a deprecation warning
• run hack/update-codegen.sh again, to see that there are no notable diffs after switching the generation script – the only changes seem to be concerned with the order of certain functions/variables

Special notes for your reviewer:

• should we consider dropping versions other than v1, especially v1alpha1 and v1beta1, maybe even v1beta2? All those versions don't work with the newer k8s releases and the recent VPA releases don't work with older k8s releases.
• should we consider generating applyconfigurations, as discussed in Make enum fields on the VPA API not pointers #5503?
• Considering we already released 1.1 without re-generating these code parts
  • how problematic is this? Do we need to cherry-pick this into 1.1 and cut a new release?
  • should we consider making hack/verify-codegen.sh a presubmit check?

Does this PR introduce a user-facing change?

Re-generated deepcopy and client files to include the recent API changes.

[nikimanoledaki]

Great! Left a couple comments 👍

[nikimanoledaki]

LGTM!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: nikimanoledaki, voelzmo
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[voelzmo]

rebased on recent master to re-trigger github action tests – somehow they were red although I didn't change anything related to the test?

[voelzmo]

rebased on recent master to re-trigger github action tests – somehow they were red although I didn't change anything related to the test?

Turned out I was wrong: the boilerplate was missing for tools.go. There were just so many Error: lines in the test output that were unrelated to my change that I didn't see the very first line that actually was helpful 🙈