chore: adds useful SQL scripts for devops (#14068)

scripts/connection-activity.sql

@@ -0,0 +1,24 @@
+-- Check all connection activity
+SELECT
+	*
+FROM
+	pg_stat_activity;
+
+-- Clear idle connections older than 15 minutes
+SELECT
+	pg_terminate_backend(pid)
+FROM
+	pg_stat_activity
+WHERE
+	state = 'idle'
+AND
+	state_change < now() - '15min'::INTERVAL;
+	
+-- Check connections by user
+SELECT
+	usename,
+	count(*)
+FROM
+	pg_stat_activity
+GROUP BY
+	usename;