logind-session: downgrade user@.service dep to Wants=

This partially reverts 52bcc872b5.

We explicitly support running without user manager,
hence only user-runtime-dir@.service should be
required.

Fixes #33405

src/login/logind-dbus.c

@@ -4353,6 +4353,7 @@ int manager_start_scope(
                 const char *slice,
                 const char *description,
                 const char * const *requires,
+                const char * const *wants,
                 const char * const *extra_after,
                 const char *requires_mounts_for,
                 sd_bus_message *more_properties,
@@ -4402,6 +4403,16 @@ int manager_start_scope(
                         return r;
         }
 
+        STRV_FOREACH(i, wants) {
+                r = sd_bus_message_append(m, "(sv)", "Wants", "as", 1, *i);
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_append(m, "(sv)", "After", "as", 1, *i);
+                if (r < 0)
+                        return r;
+        }
+
         STRV_FOREACH(i, extra_after) {
                 r = sd_bus_message_append(m, "(sv)", "After", "as", 1, *i);
                 if (r < 0)
@@ -4464,6 +4475,7 @@ int manager_start_scope(
                                         slice,
                                         description,
                                         requires,
+                                        wants,
                                         extra_after,
                                         requires_mounts_for,
                                         more_properties,

src/login/logind-dbus.h

@@ -32,6 +32,7 @@ int manager_start_scope(
                 const char *slice,
                 const char *description,
                 const char * const *requires,
+                const char * const *wants,
                 const char * const *extra_after,
                 const char *requires_mounts_for,
                 sd_bus_message *more_properties,

src/login/logind-session.c

@@ -749,15 +749,15 @@ static int session_start_scope(Session *s, sd_bus_message *properties, sd_bus_er
                         s->user->slice,
                         description,
                         /* These should have been pulled in explicitly in user_start(). Just to be sure. */
-                        STRV_MAKE_CONST(s->user->runtime_dir_unit,
-                                        SESSION_CLASS_WANTS_SERVICE_MANAGER(s->class) ? s->user->service_manager_unit : NULL),
+                        /* requires = */ STRV_MAKE_CONST(s->user->runtime_dir_unit),
+                        /* wants = */ STRV_MAKE_CONST(SESSION_CLASS_WANTS_SERVICE_MANAGER(s->class) ? s->user->service_manager_unit : NULL),
                         /* We usually want to order session scopes after systemd-user-sessions.service
                          * since the unit is used as login session barrier for unprivileged users. However
                          * the barrier doesn't apply for root as sysadmin should always be able to log in
                          * (and without waiting for any timeout to expire) in case something goes wrong
                          * during the boot process. */
-                        STRV_MAKE_CONST("systemd-logind.service",
-                                        SESSION_CLASS_IS_EARLY(s->class) ? NULL : "systemd-user-sessions.service"),
+                        /* extra_after = */ STRV_MAKE_CONST("systemd-logind.service",
+                                                            SESSION_CLASS_IS_EARLY(s->class) ? NULL : "systemd-user-sessions.service"),
                         user_record_home_directory(s->user->user_record),
                         properties,
                         error,