Revert "systemctl: when removing enablement or mask symlinks, cover both /run and...

Revert "systemctl: when removing enablement or mask symlinks, cover both /run and /etc"

We currently have packages in the archive which use
"systemctl --runtime unmask" and are broken by this change.
This is a intermediate step until it is clear whether upstream will
revert this commit or whether we will have to update affected packages
to deal with this changed behaviour.

See #902287 and https://github.com/systemd/systemd/issues/9393

This reverts commit 4910b35078ad24dcbc63f372b2fee087640201d0.

Gbp-Pq: Topic debian
Gbp-Pq: Name Revert-systemctl-when-removing-enablement-or-mask-symlink.patch