Update the Tempest plugin to point towards the new plugin

The Magnum service has split it's tests for Tempest in a seperate
repo so this patch updates it.

This patch also fixes the lint issue to use the systemd module
reload feature instead of a command.

Co-Authored-By: Jean-Philippe Evrard <jean-philippe@evrard.me>
Closes-Bug: #1747607
Depends-On: I5f1ecb71c6125c29d6487bef6c2be215c1b561c1
Change-Id: Ia4e323eda453ae3e8dacf3dcf14d175e00727b4f

tasks/magnum_init_systemd.yml

@@ -49,7 +49,8 @@
   register: systemd_init
 
 - name: Reload the systemd daemon
-  command: "systemctl daemon-reload"
+  systemd:
+    daemon_reload: true
   when: systemd_init | changed
   notify:
     - Restart magnum services

tests/os_magnum-overrides.yml

@@ -3,11 +3,11 @@ tempest_run: yes
 
 tempest_plugins:
   - name: magnum
-    repo: https://git.openstack.org/openstack/magnum
+    repo: https://git.openstack.org/openstack/magnum-tempest-plugin
     branch: master
 
 tempest_test_whitelist:
-  - magnum.tests.functional.api.v1.test_cluster.ClusterTest.test_create_cluster*
+  - magnum_tempest_plugin.tests.api.v1.test_cluster.ClusterTest.test_create_cluster*
 
 tempest_flavors:
   - name: m1.magnum