Automatic merge from submit-queue (batch tested with PRs 51114, 51233, 51024, 51053, 51197)

default field selectors

We have a lot of code around field selectors that doesn't add much value. Every gettable resources probably wants name and namespace by default and since they all use metav1 (today), we can assign that as a default. If we think we'll always have metav1 style name and namespace, then this makes a reasonable default and you can always set something different.

This removes cruft and avoids the risk of accidentally forgetting a field selector.  

@kubernetes/sig-api-machinery-misc @smarterclayton