Scripts/Ulduar: fixed hodir kill credit

Closes #15303

(cherry picked from commit 30fc4f9f63)

src/server/scripts/Northrend/Ulduar/Ulduar/boss_hodir.cpp

@@ -396,11 +396,11 @@ class boss_hodir : public CreatureScript
                     me->SetControlled(true, UNIT_STATE_STUNNED);
                     me->CombatStop(true);
 
+                    DoCastAOE(SPELL_KILL_CREDIT); /// need to be cast before changing boss faction
+                                                  /// spell will target enemies only
                     me->setFaction(35);
                     me->DespawnOrUnsummon(10000);
 
-                    DoCastAOE(SPELL_KILL_CREDIT);
-
                     _JustDied();
                 }
             }