Core/Unit: Correct speed calculus when affected by SPELL_AURA_MOD_MINIMUM_SPEED (#18136)

src/server/scripts/Northrend/IcecrownCitadel/boss_the_lich_king.cpp

@@ -1431,7 +1431,6 @@ class npc_valkyr_shadowguard : public CreatureScript
                 _events.Reset();
                 me->SetReactState(REACT_PASSIVE);
                 DoCast(me, SPELL_WINGS_OF_THE_DAMNED, false);
-                me->SetSpeedRate(MOVE_FLIGHT, 0.642857f);
             }
 
             void IsSummonedBy(Unit* /*summoner*/) override