Rancher Backup still using very old CRD generation mechanisms

[mallardduck]

Per title, BRO is still using very old poorly maintained CRD building techniques.

https://github.com/rancher/backup-restore-operator/blob/main/pkg/crds/crd.go

For QA

• General upgrade regression testing (so going from 2.14 and BRO there, to 2.15 and updated BRO)
• Overall this part of the change should not have any major side-effects
• CRDs are generated using newer tooling

[mallardduck]

This PR addresses this issue: #1008