Start daemon with Unix socket only

Mostly reproduce flow of https://github.com/docker-library/docker/blob/master/19.03/dind/dockerd-entrypoint.sh#L130
TCP socket with or without TLS isn't really needed for our usecase so
it's disable

docker.go

@@ -330,7 +330,10 @@ func commandPush(build Build, tag string) *exec.Cmd {
 
 // helper function to create the docker daemon command.
 func commandDaemon(daemon Daemon) *exec.Cmd {
-	args := []string{"--data-root", daemon.StoragePath}
+	args := []string{
+		"--data-root", daemon.StoragePath,
+		"--host=unix:///var/run/docker.sock",
+	}
 
 	if daemon.StorageDriver != "" {
 		args = append(args, "-s", daemon.StorageDriver)