This adds the annotation for having the podpreset admission controller
to skip (opt-out) manipulating the pod spec.
Also, the annotation format for what presets have acted on a pod has
been modified to add a prefix of "podpreset-". The new naming makes it such
that there is no chance of collision with the newly introduced opt-out
annotation (or future ones yet to be added).
Opt-out annotation PR:
kubernetes/kubernetes#44965
c1c6faf59b