Rename core fixtures to match the drivetrain component names

The following changes:
  common_services_deployed -> core_deployed
  sl_deployed -> stacklight_deployed

Change-Id: I6e505d2ef96053b19b2d43b0214f5a30f71ae8ea
diff --git a/tcp_tests/helpers/ext.py b/tcp_tests/helpers/ext.py
index 800367d..19bdf08 100644
--- a/tcp_tests/helpers/ext.py
+++ b/tcp_tests/helpers/ext.py
@@ -43,11 +43,11 @@
     'hardware',
     'underlay',
     'salt_deployed',
-    'common_services_deployed',
+    'core_deployed',
     'oss_deployed',
     'drivetrain_deployed',
     'openstack_deployed',
-    'sl_deployed',
+    'stacklight_deployed',
     'virtlet_deployed',
     'virtlet_ceph_deployed',
     'k8s_deployed',