This is far too confusing and difficult to maintain. For background:
11:11 yurik: jdlrobson2, do we expect to support older mediawikis ?
11:12 yurik: jdlrobson2, if not, would rather get rid of all the settings in gather.php and move to extension.json
11:13 yurik: so no need for <1.25 support, rigth?
11:13 jdlrobson2: yurik: let me fix the status quo in https://gerrit.wikimedia.org/r/#/c/194850/ and then i'm more than happy to drop < 1.25 support :)
More details are available on T87875.