Scripts/quest: Remove no longer existing quest script

src/server/game/Scripting/ScriptLoader.cpp

@@ -361,7 +361,6 @@ void AddSC_bloodmyst_isle();
 void AddSC_darkshore();
 void AddSC_desolace();
 void AddSC_durotar();
-void AddSC_dustwallow_marsh();
 void AddSC_felwood();
 void AddSC_feralas();
 void AddSC_moonglade();
@@ -1079,7 +1078,6 @@ void AddKalimdorScripts()
     AddSC_darkshore();
     AddSC_desolace();
     AddSC_durotar();
-    AddSC_dustwallow_marsh();
     AddSC_felwood();
     AddSC_feralas();
     AddSC_moonglade();