Remove hack to create pre-9.4 monitoring history table

The pg_lsn datatype was introduced in PostgreSQL 9.4, and we no
longer need to support earlier versions.

repmgr--5.2.sql

@@ -23,16 +23,7 @@ CREATE TABLE repmgr.events (
   details          TEXT NULL
 );
 
-DO $repmgr$
-DECLARE
-  DECLARE server_version_num INT;
-BEGIN
-  SELECT setting
-    FROM pg_catalog.pg_settings
-   WHERE name = 'server_version_num'
-    INTO server_version_num;
-  IF server_version_num >= 90400 THEN
-    EXECUTE $repmgr_func$
+
 CREATE TABLE repmgr.monitoring_history (
   primary_node_id                INTEGER NOT NULL,
   standby_node_id                INTEGER NOT NULL,
@@ -42,24 +33,7 @@ CREATE TABLE repmgr.monitoring_history (
   last_wal_standby_location      PG_LSN,
   replication_lag                BIGINT NOT NULL,
   apply_lag                      BIGINT NOT NULL
-)
-    $repmgr_func$;
-  ELSE
-    EXECUTE $repmgr_func$
-CREATE TABLE repmgr.monitoring_history (
-  primary_node_id                INTEGER NOT NULL,
-  standby_node_id                INTEGER NOT NULL,
-  last_monitor_time              TIMESTAMP WITH TIME ZONE NOT NULL,
-  last_apply_time                TIMESTAMP WITH TIME ZONE,
-  last_wal_primary_location      TEXT NOT NULL,
-  last_wal_standby_location      TEXT,
-  replication_lag                BIGINT NOT NULL,
-  apply_lag                      BIGINT NOT NULL
-)
-    $repmgr_func$;
-  END IF;
-END$repmgr$;
-
+);
 
 
 CREATE INDEX idx_monitoring_history_time