Stop using wrangler CRD generation helpers

[brandond]

The wrangler helpers for generating CRDs from golang types are deprecated, and do not support a bunch of nice features (including field descriptions) that controller-gen supports. We're working on moving projects over to controller-gen, and will need to update the k3s CRD creation code to sync with this.

Ref:

• Add pregenerated CRD manifests api#2
• Rework CRD generation to add docs and kubectl explain support helm-controller#281
• Rework Plan CRD generation to add docs and kubectl explain support rancher/system-upgrade-controller#369

[aganesh-suse]

Closing based on #12617