The Growth team is moving configuration to on-wiki JSON blob as part of T274520: Move Growth configuration to on-wiki JSON file. We need to be able to provide default versions of on-wiki config, depending on each wiki. The defaults will be probably determined via WIkidata, I'll file a subtask to decide that.
Write a maintenance script that can be executed from mwmaint1002. The script will determine defaults from Wikidata, and write an initial version of the configuration file to the wiki. The edit will be attributed to a system user MediaWiki default, to make it clear the edit is a part of standard software deployment process.
The script should determine the defaults for any given wiki using Wikidata items that are available at https://www.mediawiki.org/wiki/Growth/Communities/Get_the_Growth_experiments_on_your_wiki.