repmgrd: restrict BDR monitoring to two node setup

It's not safe to have more than two nodes with this kind of
"failover", so we don't need to select alternative nodes by
priority.

config.h

@@ -97,9 +97,6 @@ typedef struct
 	char		event_notification_command[MAXLEN];
 	EventNotificationList event_notifications;
 
-    /* bdr settings */
-    int			bdr_monitoring_mode;
-
 	/* barman settings */
 	char		barman_host[MAXLEN];
 	char		barman_server[MAXLEN];
@@ -132,8 +129,6 @@ typedef struct
 		"", "", "", "", "", "", \
 		/* event notification settings */ \
 		"", { NULL, NULL }, \
-		/* bdr settings */ \
-		BDR_MONITORING_LOCAL, \
 		/* barman settings */ \
 		"", "", "",	 \
 		/* undocumented test settings */ \