Revert `rm -f` deprecation use SIGKILL instead

`rm -f` was originally deprecated in favor of `rm --stop/--kill` since `rm
-f` was sending SIGTERM and potentially very slow.
Instead this will bring back `rm -f` but use SIGKILL isntead

Docker-DCO-1.1-Signed-off-by: Brian Goff <cpuguy83@gmail.com> (github: cpuguy83)
Merge pull request #7374 from cpuguy83/revert_rm_f_deprecation

Revert --stop/--kill and use SIGKILL instead