add database connection to the metrics endpoint (#12427)

* add database connection to the metrics endpoint

* bump the counts collector version to 1.2

* check for postgresql as database so to not break the tests

awx/main/tests/functional/analytics/test_metrics.py

@@ -31,6 +31,7 @@ EXPECTED_VALUES = {
     'awx_license_instance_total': 0,
     'awx_license_instance_free': 0,
     'awx_pending_jobs_total': 0,
+    'awx_database_connections_total': 1,
 }