Rename --enable-inflight-quota-handler to --enable-priority-and-fairness.
Rename --enable-inflight-quota-handler to --enable-priority-and-fairness.

The old flag name doesn't make sense with the renamed API Priority and
Fairness feature, and it's still safe to change the flag since it hasn't done
anything useful in a released k8s version yet.

Kubernetes-commit: 711c1e17209cc410440eecd3723e7b4906ca0e42

kubernetes/apiserver,kubernetes/apiserver