Disable pod security label syncer for namespaces modified by the customer

What

Don't enforce system defaults on a namespace's pod security labels, if it is managed by a user.

Why

If the managedFields (https://kubernetes.io/docs/reference/using-api/server-side-apply/#field-management) indicate that a user changed the pod security labels, we should not enforce system defaults.

A user might not be aware that the label syncer can be turned off and tries to manually change the state of the pod security profiles.

This fight between a user and the label syncer can cause violations.