♿ Make theme switcher easier to use

lib/translations/en_us.dart

@@ -312,6 +312,5 @@ const i18nEnglish = {
   'themeColorMiku': 'Miku Blue',
   'themeColorKagamine': 'Kagamine Yellow',
   'themeColorLuka': 'Luka Pink',
-  'themeColorApplied':
-      'Global theme color has been applied, dark mode theme need restart to get applied.',
+  'themeColorApplied': 'Global theme color has been applied.',
 };

lib/translations/zh_cn.dart

@@ -289,5 +289,5 @@ const i18nSimplifiedChinese = {
   'themeColorMiku': '未来色',
   'themeColorKagamine': '镜音黄',
   'themeColorLuka': '流音粉',
-  'themeColorApplied': '全局主题颜色已应用，深色模式中主题需要重启生效',
+  'themeColorApplied': '全局主题颜色已应用',
 };