patch releases: remove 1.16 at EOL
patch releases: remove 1.16 at EOL

As of the 1.16.15 release, the release-1.16 branch is no longer
receiving community support.

Signed-off-by: Tim Pepper <4807564e5a18784afafcf20dbdb5591e844b9075@vmware.com>

kubernetes/sig-release