Don't wait so long for primary/standby info and changes

While monitoring for failover, we get the changes, such as "standby was just
added", and also if a failover and promotion occurs as much as five minutes
after it happened.  This is far too long.  With 2 minutes, we can still be
conservative in polling postgres but still not take that long.

We may find that we can drop this further to 90 seconds or even 60 seconds but
this change seems like an obvious improvement with very little downside such as
too many connections to postgres.

We establish 2 very quick connections for each iteration of this loop[1], once for
the logical replication connection and once for the rails connection[2].  This
means every 2 minutes, we make 2 connections.  This should not be a big concern
even if we have tens of appliances in a complex.

[1] https://github.com/ManageIQ/manageiq-postgres_ha_admin/blob/e7e87af12da82f86e967a22700505442f61bb7b1/lib/manageiq/postgres_ha_admin/failover_monitor.rb#L51-L58
[2] https://github.com/ManageIQ/manageiq/blob/17feafb6138749996fc0e529c42e1928abb18968/lib/evm_database.rb#L174-L175

config/ha_admin.yml

@@ -1,4 +1,4 @@
 ---
 failover_attempts: 10
-db_check_frequency: 300
+db_check_frequency: 120
 failover_check_frequency: 60