fix(Scripts/SSC): do reset threat list for p3 in the right place (#18354)

init

src/server/scripts/Outland/CoilfangReservoir/SerpentShrine/boss_leotheras_the_blind.cpp

@@ -94,8 +94,6 @@ struct boss_leotheras_the_blind : public BossAI
             }
 
             me->SetUnitFlag(UNIT_FLAG_NOT_SELECTABLE);
-
-            DoResetThreatList();
             me->ClearTarget();
             me->SendMeleeAttackStop();
             scheduler.CancelGroup(GROUP_DEMON);
@@ -112,6 +110,7 @@ struct boss_leotheras_the_blind : public BossAI
                 DoCastSelf(SPELL_SUMMON_SHADOW_OF_LEOTHERAS);
             }).Schedule(6s, [this](TaskContext)
             {
+                DoResetThreatList();
                 me->RemoveUnitFlag(UNIT_FLAG_NOT_SELECTABLE);
                 me->SetStandState(UNIT_STAND_STATE_STAND);
                 me->SetReactState(REACT_AGGRESSIVE);