WA for stuck tests in docker images

  * Sometimes docker plugin unable to stop stucked image, and mark whole
    run as failed.
  * WA catch such situation, and delete|kill image forcelly via cmdline.
  * Dissadv.:
    - out of docker pipeline plugin
  * Misc:
    - remove bash-timeout => pipeline one
    - add cpus=4 as default docker docker
  * TODO: we should switch from
    docker.image("mirantis/salt:saltstack-ubuntu-xenial-salt-2017.7")
    => to any prebuild image with pre-installed salt.

Change-Id: I840ecb38bf8eaddbbfd4f3906c5296096ce15e03
1 file changed