refactor: Remove unused config

lib/config/app_config.dart

@@ -42,7 +42,6 @@ abstract class AppConfig {
   static bool hideRedactedEvents = false;
   static bool hideUnknownEvents = true;
   static bool hideUnimportantStateEvents = true;
-  static bool showDirectChatsInSpaces = true;
   static bool separateChatTypes = false;
   static bool autoplayImages = true;
   static bool sendTypingNotifications = true;

lib/config/setting_keys.dart

@@ -5,8 +5,6 @@ abstract class SettingKeys {
   static const String hideUnknownEvents = 'chat.fluffy.hideUnknownEvents';
   static const String hideUnimportantStateEvents =
       'chat.fluffy.hideUnimportantStateEvents';
-  static const String showDirectChatsInSpaces =
-      'chat.fluffy.showDirectChatsInSpaces';
   static const String separateChatTypes = 'chat.fluffy.separateChatTypes';
   static const String sentry = 'sentry';
   static const String theme = 'theme';

lib/widgets/matrix.dart

@@ -442,12 +442,6 @@ class MatrixState extends State<Matrix> with WidgetsBindingObserver {
     store
         .getItemBool(SettingKeys.hideUnknownEvents, AppConfig.hideUnknownEvents)
         .then((value) => AppConfig.hideUnknownEvents = value);
-    store
-        .getItemBool(
-          SettingKeys.showDirectChatsInSpaces,
-          AppConfig.showDirectChatsInSpaces,
-        )
-        .then((value) => AppConfig.showDirectChatsInSpaces = value);
     store
         .getItemBool(SettingKeys.separateChatTypes, AppConfig.separateChatTypes)
         .then((value) => AppConfig.separateChatTypes = value);