Fail RequisiteOf units with oneshots

Fail RequisiteOf units with oneshots

Fixes: #11422
Oneshots going to inactive directly without ever entering UNIT_ACTIVE is
considered success. This however means that if something both Requires=
and Requisites= a unit of such nature, the verify-active job getting
merged into the start job makes it lose this property of failing the
depending jobs, as there, the start job has the result JOB_DONE on
success, so we never walk over RequisiteOf units.

This change makes sure that such units always go down. It is also only
meaningful with After=, but so is Requisite= itself. Also, we also catch
cases like a oneshot having RemainAfterExit= true making us start up
properly in such a setting, but then removing it, reloading the unit,
and restarting it. In such a case, we go down due to restart propagation
before them, and our start job waits on theirs, properly failing with
the JOB_DEPENDENCY result.

This covers cases where ConditionXYZ= creates a similar situation as
well.