Regularly sync witness server repl_nodes table.

Although the witness server will resync the repl_nodes table following
a failover, other operations (e.g. removing or cloning a standby)
were previously not reflected in the witness server's copy of this
table.

As a short-term workaround, automatically resync the table at regular
intervals (defined by the configuration file parameter
"witness_repl_nodes_sync_interval_secs", default 30 seconds).

repmgr.c

@@ -1071,7 +1071,8 @@ do_master_register(void)
 										options.node_name,
 										options.conninfo,
 										options.priority,
-										repmgr_slot_name_ptr);
+										repmgr_slot_name_ptr,
+										true);
 
 	if (record_created == false)
 	{
@@ -1172,9 +1173,8 @@ do_standby_register(void)
 										options.node_name,
 										options.conninfo,
 										options.priority,
-										repmgr_slot_name_ptr);
-
-
+										repmgr_slot_name_ptr,
+										true);
 
 	if (record_created == false)
 	{
@@ -3784,7 +3784,8 @@ do_witness_create(void)
 										options.node_name,
 										options.conninfo,
 										options.priority,
-										NULL);
+										NULL,
+										true);
 
 	if (record_created == false)
 	{