lib_util: diff_colorized always exits 0
lib_util: diff_colorized always exits 0

Since diff_colorized is intended for human consumption (log output),
always return true so that diff output doesn't cause things to halt.

Somehow I thought `git diff` was always exiting with 0, regardless of
whether the two files differed or not.  Turns out it _will_ exit
non-zero if files differ.

kubernetes/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io