Fix connection query metric for PG 9.6 (#212) (#213)

Co-authored-by: Keith Fiske <[email protected]>

exporter/postgres/queries_pg96.yml

@@ -12,7 +12,7 @@ ccp_connection_stats:
         , idle_in_txn
         , (select coalesce(extract(epoch from (max(now() - state_change))),0) from monitor.pg_stat_activity() where state = 'idle in transaction') as max_idle_in_txn_time
         , (select coalesce(extract(epoch from (max(now() - query_start))),0) from monitor.pg_stat_activity() where state <> 'idle') as max_query_time
-        , (select coalesce(extract(epoch from (max(now() - query_start))),0) from pg_catalog.pg_stat_activity where backend_type = 'client backend' and wait_event_type = 'Lock' ) as max_blocked_query_time
+        , (select coalesce(extract(epoch from (max(now() - query_start))),0) from pg_catalog.pg_stat_activity where wait_event_type = 'Lock' ) as max_blocked_query_time
         , max_connections
         from (
                 select count(*) as total