Add HA cases for rabbitmq and galera

- kill rabbitmq_server on random node
- kill mysql server on node with maximum mysql connections

Change-Id: I8cf1aab4a4213c339ddefcecaa86d9a80d52acdb
diff --git a/tcp_tests/tests/system/conftest.py b/tcp_tests/tests/system/conftest.py
index ec3846d..64288ab 100644
--- a/tcp_tests/tests/system/conftest.py
+++ b/tcp_tests/tests/system/conftest.py
@@ -52,6 +52,7 @@
     # oss_fixtures
     'oss_actions',
     'oss_deployed',
+    'oss_sl_os_deployed',
     # decapod_fixtures
     'decapod_actions',
     'decapod_deployed',