pid1: order .automount units after local-fs-pre.target

From the bug:
> According to the documentation of systemd.automount if the automoint point is
> automagically created if it doesn't exist yet. This ofcourse means the
> filesystem underneath has to be writable, which for / means not only does
> -.mount need to be started but also systemd-remount-fs.service has to be run,
> which isn't guaranteed by the default automount dependencies.
>
> For .mount units there is an automatic default After= dependency on
> local-fs-pre.target, would probably make sense to do the same for automount
> units to avoid it failing on the corner-case where it has to create directory.

Fixes #13306.

src/core/automount.c

@@ -152,6 +152,10 @@ static int automount_add_default_dependencies(Automount *a) {
         if (!MANAGER_IS_SYSTEM(UNIT(a)->manager))
                 return 0;
 
+        r = unit_add_dependency_by_name(UNIT(a), UNIT_AFTER, SPECIAL_LOCAL_FS_PRE_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+        if (r < 0)
+                return r;
+
         r = unit_add_two_dependencies_by_name(UNIT(a), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
         if (r < 0)
                 return r;