cleanup-update.sh: use explicity cleanup cmds

In order to ensure that we remove non-running
containers and all dangling images, let's explicitly
call 'docker [image|container] prune' instead of
relying on 'docker system' to figure out the
right thing to do.

Signed-off-by: Kelley Spoon <kelley.spoon@linaro.org>
Change-Id: Ifbdfe65b9a5b949296de309f7cdf1e7386780d45
1 file changed