Following on from T200650: Deprecate/obsolete $wgWikimediaJenkinsCI...
It's not really well documented how/when to do CI specific config. $wgWikimediaJenkinsCI is kinda deprecated...
There is MW_PHPUNIT_TEST too..
Especially relevant with T262443: Do not hit actual urls during phpunit tests, T265628: Identify which extensions' tests make HTTP requests and so are now broken post-T262443, where extensions want to provide sensible defaults (which may be a URL, and may result in a HTTP request in normal circumstances), but then this fails during CI because it tried to do a HTTP request...