In install_docker.sh, we will restart docker service, then connect
to /var/run/docker.sock with retry mechanism.
At the first contacting with /var/run/docker.sock, when docker
service is not ready, it may complain some error.
Mute this false alarm.
Change-Id: If00a18d2e3ddee951662e272d47ae84215f16ad2
Closes-Bug: #1252087