fix(Core/Scripts): Fix boss scripts resetting during death/defeat RP after threat system port (#25185)

Co-authored-by: blinkysc <blinkysc@users.noreply.github.com>
Co-authored-by: Treeston <treeston.mmoc@gmail.com>

src/server/scripts/EasternKingdoms/MagistersTerrace/boss_felblood_kaelthas.cpp

@@ -190,11 +190,10 @@ struct boss_felblood_kaelthas : public BossAI
             damage = me->GetHealth() - 1;
             if (me->isRegeneratingHealth())
             {
-                me->CombatStop();
                 me->CastStop();
                 me->SetRegeneratingHealth(false);
                 me->SetUnitFlag(UNIT_FLAG_DISABLE_MOVE);
-                me->SetImmuneToAll(true);
+                me->SetImmuneToAll(true, true);
                 me->SetReactState(REACT_PASSIVE);
                 LapseAction(ACTION_REMOVE_FLY);
                 scheduler.CancelAll();

src/server/scripts/EasternKingdoms/SunwellPlateau/boss_kalecgos.cpp

@@ -161,7 +161,6 @@ struct boss_kalecgos : public BossAI
 
             me->m_Events.AddEventAtOffset([&] {
                 me->SetReactState(REACT_PASSIVE);
-                me->CombatStop();
                 me->RemoveAllAuras();
                 me->SetUnitFlag(UNIT_FLAG_NON_ATTACKABLE);
                 Talk(SAY_EVIL_ENRAGE);