Remove offline installer to install shim-process

Removes the need for the offline installer to install the shim process
and instead installs the shim process as part of the packaging.

May be easier in the future to just package the shim process on it's own
but that'll come after this 18.09 release

Signed-off-by: Eli Uriegas <eli.uriegas@docker.com>

contrib/init/systemd/docker.service

@@ -6,9 +6,6 @@ After=network-online.target firewalld.service
 Wants=network-online.target
 
 [Service]
-# Install containerd-shim-process if it's not already installed
-ExecStartPre=/usr/libexec/containerd-offline-installer /var/lib/containerd-offline-installer/containerd-shim-process.tar docker.io/docker/containerd-shim-process
-
 # the default is not to use systemd for cgroups because the delegate issues still
 # exists and systemd currently does not support the cgroup feature set required
 # for containers run by docker