Fixes TestRmiForceWithExistingContainers test to make it use
`busybox` image rather than /docker-busybox hardcoded path
and rebuilding image.
Signed-off-by: Ahmet Alp Balkan <ahmetalpbalkan@gmail.com>
Upstream-commit: 57d34241fdff146eaeae748c959940489335ed2a
Component: engine