Core/Vehicles: update the power display of vehicles before being added to world to avoid building unnecessary update_object packets right after spawning them

Port From (https://github.com/TrinityCore/TrinityCore/commit/f4f56c105fabf33398d332c09c8e331bc4025192)

Source/Game/Entities/Creature/Creature.cs

@@ -1532,7 +1532,8 @@ namespace Game.Entities
             }
 
             if (vehId != 0)
-                CreateVehicleKit(vehId, entry, true);
+                if (CreateVehicleKit(vehId, entry, true))
+                    UpdateDisplayPower();
 
             return true;
         }

Source/Game/Entities/Vehicle.cs

@@ -72,8 +72,6 @@ namespace Game.Entities
 
         public void Install()
         {
-            _me.UpdateDisplayPower();
-
             _status = Status.Installed;
             if (GetBase().IsTypeId(TypeId.Unit))
                 Global.ScriptMgr.OnInstall(this);