Core/Combat: Disable triggers entering combat

Port From (https://github.com/TrinityCore/TrinityCore/commit/1dfcb7086e17902f0904ee6c09bc55a229b65cc1)

Source/Framework/Constants/CreatureConst.cs

@@ -210,6 +210,7 @@ namespace Framework.Constants
         UnitIsQuestBoss = 0x80000000 // Not verified
     }
 
+    [Flags]
     public enum CreatureFlagsExtra : uint
     {
         InstanceBind = 0x01,       // Creature Kill Bind Instance With Killer And Killer'S Group
@@ -225,7 +226,7 @@ namespace Framework.Constants
         GhostVisibility = 0x400,       // creature will be only visible for dead players
         UseOffhandAttack = 0x800, // creature will use offhand attacks
         NoSellVendor = 0x1000,       // players can't sell items to this vendor
-        Unused13 = 0x2000,
+        NoCombat = 0x2000,         // creature is not allowed to enter combat
         Worldevent = 0x4000,       // Custom Flag For World Event Creatures (Left Room For Merging)
         Guard = 0x8000,       // Creature Is Guard
         Unused16 = 0x00010000,
@@ -246,7 +247,7 @@ namespace Framework.Constants
         Unused31 = 0x80000000,
 
         // Masks
-        AllUnused = (Unused13 | Unused16 | Unused22 | Unused23 | Unused24 | Unused25 | Unused26 | Unused27 | Unused31),
+        AllUnused = (Unused16 | Unused22 | Unused23 | Unused24 | Unused25 | Unused26 | Unused27 | Unused31),
 
         DBAllowed = (0xFFFFFFFF & ~(AllUnused | DungeonBoss))
     }