The PageTriage browser tests are not set up to run in MediaWiki-Vagrant.
There is no browser_tests => true (https://git.wikimedia.org/blob/mediawiki%2Fvagrant.git/66b6677e009475530d289a8624568a2c587c50c4/puppet%2Fmodules%2Frole%2Fmanifests%2Fpagetriage.pp), but adding that was not sufficient to get it work for me.
Firefox started up, but never made it to any page. See https://gerrit.wikimedia.org/r/#/c/186949/ .