Scripts/Grim Batol: use a direct DespawnOrUnsummon call instead of corpse delay for Drahga's Invoked Flaming Spirits

src/server/scripts/EasternKingdoms/GrimBatol/boss_drahga_shadowburner.cpp

@@ -448,7 +448,6 @@ struct npc_drahga_invoked_flaming_spirit : public ScriptedAI
 {
     npc_drahga_invoked_flaming_spirit(Creature* creature) : ScriptedAI(creature)
     {
-        me->SetCorpseDelay(3);
         me->SetReactState(REACT_PASSIVE);
         me->SetWalk(true);
     }
@@ -465,6 +464,11 @@ struct npc_drahga_invoked_flaming_spirit : public ScriptedAI
             DoCastSelf(SPELL_QUIETE_SUICIDE);
     }
 
+    void JustDied(Unit* /*killer*/) override
+    {
+        me->DespawnOrUnsummon(3s);
+    }
+
     void UpdateAI(uint32 diff) override
     {
         if (!UpdateVictim())