Add a missing symlink for /opt/gitlab/init/sshd to make `gitlab-ctl stop` work in Docker

In a Docker container, running gitlab-ctl stop would return an error code of 127, since /opt/gitlab/init/sshd did not exist.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/2406

docker/assets/wrapper

@@ -72,6 +72,7 @@ fi
 echo "Preparing services..."
 rm -f /opt/gitlab/service/*
 ln -s /opt/gitlab/sv/sshd /opt/gitlab/service
+ln -s /opt/gitlab/embedded/bin/sv /opt/gitlab/init/sshd
 mkdir -p /var/log/gitlab/sshd
 # Start service manager