Only in one file. There is two more, but I will update it.
kizule@DESKTOP-M9SBSVQ:~/development/vagrant$ git grep wgLogo LocalSettings.php:$wgLogos = [ puppet/modules/mediawiki/templates/multiwiki/LoadWgConf.php.erb: 'wgLogo' => array( puppet/modules/role/manifests/labs_initial_content.pp: wgLogo => '/labs_mediawiki_logo.png', kizule@DESKTOP-M9SBSVQ:~/development/vagrant$
Yeah, sorry for the vague task, this is about the files generated in settings.d. (settings.d/wikis/<wiki>/LocalSettings.php also has wgLogo but maybe that's created by the installer, not Vagrant?)