Combat/Threat: Split ThreatManager::NotifyDisengaged off from ThreatManager::ClearAllThreat. NotifyDisengaged signifies intent to clear the engagement flag, and should only be called from AI.

Port From (https://github.com/TrinityCore/TrinityCore/commit/38d7c1530a65a7ff1bd10775c4a35269b2416538)

Source/Game/AI/CoreAI/CreatureAI.cs

@@ -224,18 +224,15 @@ namespace Game.AI
             me.RemoveAurasOnEvade();
 
             // sometimes bosses stuck in combat?
-            me.GetThreatManager().ClearAllThreat();
             me.CombatStop(true);
+            me.GetThreatManager().NotifyDisengaged();
             me.SetLootRecipient(null);
             me.ResetPlayerDamageReq();
             me.SetLastDamagedTime(0);
             me.SetCannotReachTarget(false);
             me.DoNotReacquireTarget();
 
-            if (me.IsInEvadeMode())
-                return false;
-
-            return true;
+            return !me.IsInEvadeMode();
         }
 
         public CypherStrings VisualizeBoundary(int duration, Unit owner = null, bool fill = false)

Source/Game/AI/CoreAI/GuardAI.cs

@@ -48,15 +48,15 @@ namespace Game.AI
             {
                 me.GetMotionMaster().MoveIdle();
                 me.CombatStop(true);
-                me.GetThreatManager().ClearAllThreat();
+                me.GetThreatManager().NotifyDisengaged();
                 return;
             }
 
             Log.outDebug(LogFilter.Unit, "Guard entry: {0} enters evade mode.", me.GetEntry());
 
             me.RemoveAllAuras();
-            me.GetThreatManager().ClearAllThreat();
             me.CombatStop(true);
+            me.GetThreatManager().NotifyDisengaged();
 
             me.GetMotionMaster().MoveTargetedHome();
         }

Source/Game/AI/ScriptedAI/ScriptedEscortAI.cs

@@ -134,8 +134,8 @@ namespace Game.AI
         public override void EnterEvadeMode(EvadeReason why = EvadeReason.Other)
         {
             me.RemoveAllAuras();
-            me.GetThreatManager().ClearAllThreat();
             me.CombatStop(true);
+            me.GetThreatManager().NotifyDisengaged();
             me.SetLootRecipient(null);
 
             if (HasEscortState(EscortState.Escorting))

Source/Game/AI/ScriptedAI/ScriptedFollowerAI.cs

@@ -126,8 +126,8 @@ namespace Game.AI
                 return;
 
             me.RemoveAllAuras();
-            me.GetThreatManager().ClearAllThreat();
             me.CombatStop(true);
+            me.GetThreatManager().NotifyDisengaged();
             me.SetLootRecipient(null);
             me.SetCannotReachTarget(false);
             me.DoNotReacquireTarget();