systemd: set --containerd socket patch to prevent race-condition
systemd: set --containerd socket patch to prevent race-condition

containerd is now running as a separate service, and should
no longer be started as a managed child-process of dockerd.

The dockerd service already specifies that it should be started
`After` the containerd.service, but there is still a race
condition, where containerd is started, but its socket is not yet
created.

In that situation, `dockerd` detects that the containerd socket
is missing, and will start a new instance of containerd (as a
managed child-process), which causes live-restore to fail.

This patch explicitly sets the `--containerd` daemon option.
If this option is set, `dockerd` will not start a new instance
of containerd.

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

Ramzec/docker,jimjag/docker,paralin/docker,docker/docker,nawawi/docker,gnailuy/docker,mahak/docker,docker/docker,Mokolea/docker,paralin/docker,Ramzec/docker,Ramzec/docker,yosifkit/docker,jameszhan/docker,Mokolea/docker,nalind/docker,jimjag/docker,bearstech/moby,moby/moby,cpuguy83/docker,thaJeztah/docker,vdemeester/docker,nawawi/docker,docker/docker,gnailuy/docker,nawawi/docker,mahak/docker,cpuguy83/docker,Mokolea/docker,flavio/docker,AkihiroSuda/docker,paralin/docker,mahak/docker,trebonian/docker,mahak/docker,moul/docker,thaJeztah/docker,moby/moby,nawawi/docker,bearstech/moby,moul/docker,AkihiroSuda/docker,jameszhan/docker,trebonian/docker,thaJeztah/docker,cpuguy83/docker,konstruktoid/docker-upstream,gnailuy/docker,paralin/docker,moby/moby,moul/docker,konstruktoid/docker-upstream,Ramzec/docker,djs55/docker,bearstech/moby,trebonian/docker,Mokolea/docker,konstruktoid/docker-upstream,jameszhan/docker,moby/moby,bearstech/moby,nalind/docker,moul/docker,djs55/docker,AkihiroSuda/docker,jthelin/docker,jimjag/docker,yosifkit/docker,nalind/docker,yosifkit/docker,thaJeztah/docker,konstruktoid/docker-upstream,vdemeester/docker,djs55/docker,flavio/docker,flavio/docker,AkihiroSuda/docker,gnailuy/docker,jthelin/docker,cpuguy83/docker,vdemeester/docker,flavio/docker,trebonian/docker,yosifkit/docker,jimjag/docker,nalind/docker