devinstall_test: use the chromite.lib.vm module

Many of the vm-related functions in devinstall_tests.py have been
moved to the new moudle chromite/lib/vm.py to increase
reusability. This CL modifies devinstall_test.py to use the new vm
module.

BUG=chromium:336638
CQ-DEPEND=CL:184272
TEST=canary trybot run

Change-Id: I032922dd6fabb7214845d9439246a4cb23335f14
Reviewed-on: https://chromium-review.googlesource.com/184531
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Yu-Ju Hong <yjhong@chromium.org>
Tested-by: Yu-Ju Hong <yjhong@chromium.org>
1 file changed