replace generate-internal-groups with newer kube-codegen

[SimonTheLeg]

-- Just putting this already here as draft, so I don't forget it in the future --

What this PR does / why we need it: Allows for using make make update-codegen without having your code inside GOPATH, which is in line with Go development standards. In addition resolves "unsupported type" warnings like this one

W0619 10:30:57.813447   34549 parse.go:863] Making unsupported type entry "T" for: &types.TypeParam{check:(*types.Checker)(nil), id:0x1, obj:(*types.TypeName)(0xc00fed58b0), index:0, bound:(*types.Named)(0xc0000221c0)}
Generating defaulters

What type of PR is this?

/kind cleanup

Special notes for your reviewer:

Ran make update-codegen afterwards to ensure that there are no changes in the generated code.

Does this PR introduce a user-facing change? Then add your Release Note here:

NONE

Documentation:

NONE