k8s-openapi vendor size

[cgwalters]

OK yeah I didn't notice this at the time, but k8s-openapi has...an absolutely incredible amount of generated source code.

$ du -sc vendor | sort -nr
197216  total
62304   k8s-openapi
6924    linux-raw-sys
5420    linux-raw-sys-0.3.6
5188    encoding_rs
4868    tokio
4400    libc
3928    vcpkg
2848    regex-automata
2636    rustix

I think we can trim this; we just want the core type definitions and CRD stuff. This issue is problematic enough that we should maybe try dropping the dependency entirely.

Upstream link: Arnavion/k8s-openapi#148