Clean up all missing EntitySystem proxy method uses (#38353)

Content.Server/Examine/ExamineSystem.cs

@@ -51,7 +51,7 @@ namespace Content.Server.Examine
             var entity = GetEntity(request.NetEntity);
 
             if (session.AttachedEntity is not {Valid: true} playerEnt
-                || !EntityManager.EntityExists(entity))
+                || !Exists(entity))
             {
                 RaiseNetworkEvent(new ExamineSystemMessages.ExamineInfoResponseMessage(
                     request.NetEntity, request.Id, _entityNotFoundMessage), channel);