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/tests/system/test_upgrade_stacklight.py b/tcp_tests/tests/system/test_upgrade_stacklight.py
index e946185..afad0c8 100644
--- a/tcp_tests/tests/system/test_upgrade_stacklight.py
+++ b/tcp_tests/tests/system/test_upgrade_stacklight.py
@@ -25,7 +25,7 @@
     @pytest.mark.grab_versions
     @pytest.mark.fail_snapshot
     def test_upgrade_stacklight(self, underlay, config,
-                                hardware, sl_actions, sl_deployed):
+                                hardware, sl_actions, stacklight_deployed):
         """Runner
 
         Scenario:
@@ -42,19 +42,19 @@
         sl_actions.install(commands, label='Upgrade SL services')
         hardware.create_snapshot(name='sl_v1_upgraded')
 
-        mon_nodes = sl_deployed.get_monitoring_nodes()
+        mon_nodes = stacklight_deployed.get_monitoring_nodes()
         LOG.debug('Mon nodes list {0}'.format(mon_nodes))
 
 
 # Run SL component tetsts
-        sl_deployed.run_sl_functional_tests(
+        stacklight_deployed.run_sl_functional_tests(
             'cfg01',
             '/root/stacklight-pytest/stacklight_tests/',
             'tests',
             'tests/prometheus')
 
 # Download report
-        sl_deployed.download_sl_test_report(
+        stacklight_deployed.download_sl_test_report(
             'cfg01',
             '/root/stacklight-pytest/stacklight_tests/report.xml')
         LOG.info("*************** DONE **************")