chore(PCH): remove "ScriptPCH.h" from cpp scripts (#1423)

remove "ScriptPCH.h" from cpp scripts as it is intended to be used as precompiled header for the build process only

src/server/scripts/EasternKingdoms/Gnomeregan/instance_gnomeregan.cpp

@@ -2,8 +2,9 @@
  * Originally written by Xinef - Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
 */
 
+#include "Player.h"
+#include "SpellScript.h"
 #include "ScriptMgr.h"
-#include "ScriptPCH.h"
 #include "InstanceScript.h"
 #include "PassiveAI.h"