Refactor options to enabled backends

Aodh can use only one database so having multiple options per backend
software is very redundant.

Also, gnocchi and prometheus are used for the same purpose so can use
a single option instead.

Change-Id: I134cf61d8137409ef5f5d959177e349781110eaa
diff --git a/telemetry_tempest_plugin/config.py b/telemetry_tempest_plugin/config.py
index 94b6e1b..ad4ea85 100644
--- a/telemetry_tempest_plugin/config.py
+++ b/telemetry_tempest_plugin/config.py
@@ -14,6 +14,7 @@
 #    under the License.
 
 from oslo_config import cfg
+from oslo_config import types
 
 
 service_option = [cfg.BoolOpt('ceilometer',
@@ -86,18 +87,14 @@
 ]
 
 telemetry_services_opts = [
-    cfg.BoolOpt('aodh_gnocchi',
-                default=False,
-                help="Can telemetry plugin expect gnocchi backend"),
-    cfg.BoolOpt('aodh_mysql',
-                default=False,
-                help="Can telemetry plugin expect mysql backend"),
-    cfg.BoolOpt('aodh_postgre',
-                default=False,
-                help="Can telemetry plugin expect postgre backend"),
-    cfg.BoolOpt('aodh_prometheus',
-                default=False,
-                help="Can telemetry plugin expect prometheus backend"),
+    cfg.ListOpt('metric_backends',
+                default=[],
+                item_type=types.String(choices=['gnocchi', 'prometheus']),
+                help="Backend store used to store metrics"),
+    cfg.StrOpt('alarm_backend',
+               default='mysql',
+               choices=['mysql', 'postgresq'],
+               help="Database used by the aodh service"),
 ]
 
 event_opts = [