fix(Core/Raid): Vault of Archavon stomp (#1871)

- Archavon will stomp the ground, dealing approximately 4,000 unmitigable damage to everyone and stunning them for 2 seconds. At the same time, he'll Impale his highest aggro target, removing it from the fight for 8 seconds.

src/server/scripts/Northrend/VaultOfArchavon/boss_archavon.cpp

@@ -121,7 +121,6 @@ class boss_archavon : public CreatureScript
                         sprintf(buffer, "Archavon the Stone Watcher lunges for %s!", me->GetVictim()->GetName().c_str());
                         me->MonsterTextEmote(buffer, 0);
                         me->CastSpell(me->GetVictim(), RAID_MODE(SPELL_STOMP_10, SPELL_STOMP_25), false);
-                        me->GetVictim()->KnockbackFrom(me->GetPositionX(), me->GetPositionY(), 3.0f, 40.0f);
                         events.RepeatEvent(45000);
                         events.ScheduleEvent(EVENT_IMPALE, 3000);
                         break;