move MANAGER_IS_RELOADING() check into manager_recheck_{dbus|journal}() (#8510)

move MANAGER_IS_RELOADING() check into manager_recheck_{dbus|journal}() (#8510)

Let's better check this inside of the call than before it, so that we
never issue this while reloading, even should these calls be called due
to other reasons than just the unit notify.

This makes sure the reload state is unset a bit earlier in
manager_reload() so that we can safely call this function from there and
they do the right thing.

Follow-up for e63ebf71edd7947f29389c72e851d8df5c7bedda.