Core/AI: EscortAI init logic moved from JustAppeared to InitializeAI. There are no escort NPCs using compatibility mode anymore, so this is equivalent.

As a result, inheriting scripts calling Start in on-create hooks (like JustSummoned) will now work properly again.

Tagging #20310.

# Conflicts:
#	src/server/game/AI/ScriptedAI/ScriptedEscortAI.h

src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp

@@ -108,7 +108,7 @@ void EscortAI::JustDied(Unit* /*killer*/)
     }
 }
 
-void EscortAI::JustAppeared()
+void EscortAI::InitializeAI()
 {
     _escortState = STATE_ESCORT_NONE;
 
@@ -120,8 +120,6 @@ void EscortAI::JustAppeared()
 
     if (me->GetFaction() != me->GetCreatureTemplate()->faction)
         me->RestoreFaction();
-
-    Reset();
 }
 
 void EscortAI::ReturnToLastPoint()

src/server/game/AI/ScriptedAI/ScriptedEscortAI.h

@@ -40,10 +40,10 @@ struct TC_GAME_API EscortAI : public ScriptedAI
         explicit EscortAI(Creature* creature);
         ~EscortAI() { }
 
+        void InitializeAI() override;
         void UpdateAI(uint32 diff) override; // the "internal" update, calls UpdateEscortAI()
         void MoveInLineOfSight(Unit* who) override;
         void JustDied(Unit*) override;
-        void JustAppeared() override;
         void ReturnToLastPoint();
         void EnterEvadeMode(EvadeReason /*why*/ = EVADE_REASON_OTHER) override;
         void MovementInform(uint32, uint32) override;