fix(collector-webhook): ensure stabilizationWindowSeconds validation matches k8s.io/api/autoscaling/v2 requirements

[onematchfox]

Description:

This PR:

• ensures that the validation of autoscaler.behaviour.scale[Down|Up].stabilizationWindowSeconds matches the requirements of the upstream module k8s.io/api/autoscaling/v2/types.go
• adjusts the error message to report that scale[Down|Up].stabilizationWindowSeconds in specific is invalid rather than referring to the entire object.

Link to tracking Issue(s):

• Resolves: Incorrect validation and error message of stabilizationWindowSeconds in autoscaler behaviour #3345

Testing:

Existing tests have been updated to match the new requirements.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: onematchfox / name: Brian Fox (093411c, d43d0a1, 1488e80)

[swiatekm]

Thank you for the contribution! Could you add a changelog entry for this fix? make chlog-new will generate a template you can fill out.

The change itself looks good to me. One thing I don't really understand is why the struct we're importing from k8s.io/api/autoscaling doesn't come with the right validations in the first place. If we declared it on our own, we could easily validate it via OpenAPI in the CRD, not sure why Kubernetes itself can't do that.

[onematchfox]

Could you add a changelog entry for this fix? make chlog-new will generate a template you can fill out.

Done. Sorry I missed that.

One thing I don't really understand is why the struct we're importing from k8s.io/api/autoscaling doesn't come with the right validations in the first place. If we declared it on our own, we could easily validate it via OpenAPI in the CRD, not sure why Kubernetes itself can't do that.

Yeah, I'm not sure about that either. All I can add is that in trying to understand why this code was there I tracked it back to #1077.