[Maintenance] Change menu entry to avoid deprecation messages
This PR aims to remove from test logs messages like:
DEPRECATION WARNING: Using menu.item in menu_overwrite context is deprecated. Use menu.add_item (called from block in <main> at /code/config/initializers/decidim.menu.rb:2)
DEPRECATION WARNING: Using menu.item in menu_overwrite context is deprecated. Use menu.add_item (called from block in <main> at /code/config/initializers/decidim.menu.rb:6)
DEPRECATION WARNING: Using menu.item in menu_overwrite context is deprecated. Use menu.add_item (called from block in <main> at /code/config/initializers/decidim.menu.rb:10)
DEPRECATION WARNING: Using menu.item in menu_overwrite context is deprecated. Use menu.add_item (called from block in <main> at /code/config/initializers/decidim.menu.rb:15)