profile: Change "Invisible mode" toggle to more neutral "list button" style

Author: chrisbobbe

lib/widgets/profile.dart

@@ -140,6 +140,7 @@ class _InvisibleModeToggle extends StatelessWidget {
             ? zulipLocalizations.turnOnInvisibleModeErrorTitle
             : zulipLocalizations.turnOffInvisibleModeErrorTitle),
         builder: (value, handleRequestNewValue) => ZulipMenuItemButton(
+          style: ZulipMenuItemButtonStyle.list,
           label: zulipLocalizations.invisibleMode,
           onPressed: () => handleRequestNewValue(!value),
           toggle: Toggle(value: value, onChanged: handleRequestNewValue))),