Fix a bunch of compiler warnings (#10518)

Content.Server/Chat/Managers/ChatManager.cs

@@ -36,7 +36,6 @@ namespace Content.Server.Chat.Managers
         [Dependency] private readonly IAdminLogManager _adminLogger = default!;
         [Dependency] private readonly IServerPreferencesManager _preferencesManager = default!;
         [Dependency] private readonly IConfigurationManager _configurationManager = default!;
-        [Dependency] private readonly IMapManager _mapManager = default!;
         [Dependency] private readonly IEntityManager _entityManager = default!;
 
         private StationSystem _stationSystem = default!;