Update tmp cleanup on chrotomation3

Remove "*-llvm-next-nightly" images from chroot /tmp.
Updated CleanChromeOsImageFiles which now deletes directories with
rmtree. This should fix the problem with cron job auto delete.

BUG=None
TEST=Tested with --dry_run on chrotomation3.

Change-Id: If8458540e009c50dec829f14c47581fdd7be305e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2202728
Tested-by: Denis Nikitin <denik@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
1 file changed