Remove BDR 2.x support

The BDR 2.x support was conceptual only and was never used in
production. As BDR 2.x will be EOL'd shortly, there is no risk it will
be needed.

repmgr--5.0--5.1.sql

@@ -1,3 +1,5 @@
 -- complain if script is sourced in psql, rather than via CREATE EXTENSION
 \echo Use "CREATE EXTENSION repmgr" to load this file. \quit
 
+DROP FUNCTION am_bdr_failover_handler(INT);
+DROP FUNCTION unset_bdr_failover_handler();