Terminal API failures when creating child resources don't trigger Ready=False

From https://github.com/knative/serving/issues/13053

A misplaced annotation prevented the SKS from being created since it failed validation. But this didn't cause the PodAutoscaler to flip to Ready=False.

There are probably other classes of this error throughout the codebase especially since any mutating webhook could inject a failure at any point. ie. rejecting deployment creation because of some security policy.

Note: terminal implies the creation/update requests will never succeed

Start by reading the linked context in issue 13053 and tracing how SKS creation failures are reported to the PodAutoscaler. Check the paths that handle child-resource creation and mutating webhook rejection, then verify that terminal failures cause Ready=False without retrying indefinitely. Done means the behavior is covered for the described validation failure and comparable terminal creation or update errors.

Written by the indexing model from the issue text.