Disable Gravatar in WP, BuddyPress and bbPress – but still have avatars?

According to this site https://wefoster.co/completely-disable-the-use-of-gravatars-on-your-buddypress-site/ it should be possible to add a single line of code to a bp-custom.php file in order to disable Gravatar (though I’m not sure if it’s for Buddypress only, or it’s supposed to work for WP in general).

However, I can’t find that file under Plugins or Plugins/Buddypress. Perhaps it simply doesn’t exist anymore, given the fact that the link is 6-7 years old…