Core/Spells: Fire OnEffectSuccessfulDispel for SPELL_EFFECT_DISPEL_MECHANIC

Port From (https://github.com/TrinityCore/TrinityCore/commit/9f401946d3b2c246469b5b2702a5d08c0472b4fa)

Source/Game/Spells/SpellEffects.cs

@@ -3894,6 +3894,8 @@ namespace Game.Spells
                 dispel_list.RemoveAt(0);
             }
 
+            CallScriptSuccessfulDispel(effectInfo.EffectIndex);
+
             m_UniqueTargetInfo.Find(p => p.TargetGUID == unitTarget.GetGUID()).ProcHitMask |= ProcFlagsHit.Dispel;
         }