Fix behavior when running dockerctl start --attach

--attach option skips check_ready steps, which would only
run after a container was killed. This led to unnecessary
checks that were run when the container is stopped. Now the
program exits quickly so supervisor can restart the container
as intended.

Additionally, consolidated cobbler checks so that it fails in
16 minutes intead of 32.

Change-Id: I4d3c6e20b8dec0d11af46080fe6941b6b34cae4a
Closes-Bug: #1393342
(cherry picked from commit 68ef000b8cab70f56944040afcf7d5d0e5f34bbf)
Merge "Fix behavior when running dockerctl start --attach" into stable/5.1