fix(DB/graveyard): Fix Hearthglen Spirit Healer (#6206)

The graveyard (id: 1451) in Western Plaguelands near Hearthglen was
mistakenly assigned to Eastern Plaguelands instead, so players dying
near Hearthglen would resurrect at a graveyard further away.
The graveyard has been reassigned to the WPL zone.

- Closes #6204
- Closes chromiecraft/chromiecraft#765

data/sql/updates/pending_db_world/rev_1622718211042013969.sql

@@ -0,0 +1,3 @@
+INSERT INTO `version_db_world` (`sql_rev`) VALUES ('1622718211042013969');
+
+UPDATE `graveyard_zone` SET `GhostZone` = 28, `Comment` = 'Western Plaguelands, Hearthglen - Western Plaguelands' WHERE `ID` = 1451;