This is the second time I've found an odd setting coming from CirrusSearch's tests/jenkins/Jenkins.php .
If this needs to load for browser tests and/or Jenkins, it should only load for Jenkins. Loading it for normal MediaWiki-Vagrant usage interferes with completely different things.
I was researching the effects of the Researcher group, and then I found out *all* users somehow had deleterevision (usually granted to admin-type users). After grepping through all MediaWiki-Vagrant extensions, I discovered it was coming from
$wgGroupPermissions[ '*' ][ 'deleterevision' ] = true;
This is just an example, though. This file just should only be loaded when actually necessary.
This has been discussed before at T73778: CirrusSearch tests should be able to pass with wgCapitalLinks = true and https://gerrit.wikimedia.org/r/#/c/155861/ , but without a solution thus far.