Comment 34 for bug 1913421

Fixes for iteration #3:
- the leading and trailing _ was for Bionic as 2.11 stored the version differently (added in v.25), since we will test if it actually loads old modules we will have an extra check if it works that way once all other things are resolved.
- Fixed Bionic start (missed postinst; Focal finds and acts on .mount file ind debian/* so it doesn't need the same)
- Focal still has the "deb-systemd-invoke stop" section even without us calling dh_*systemd
  in d/rules. It automatically picks up the unit and decides that it is good to act on it :-/
  Now trying --no-start
- Focal did actually copy the content as planned, but afterwards prerm stopped the mount
  unit and then a new start had new empty content. Hopefully the --no-enable --no-start will
  make dh leave it alone for our handling as intended