recipes: move systemd services to PN

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
packagegroup-shr-systemd: drop runtime dependency on openssh-sshd-systemd

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
systemd-machine-units: fix service installation

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>