Currently job runners and videoscalers have a very custom mediawiki site config that allows calling to /rpc/RunSingleJob.php but disallows calling normal MediaWiki entrypoints.
In order to migrate job execution to the new REST endpoint T244826, we need to be able to call w/rest.php/eventbus/v0/internal/job/execute on job runners and vide scalers. The selection of the wiki can be done via the Host header. So, I guess a normal MW site config should be applied to jobrunners and videoscalers.
For the transitional period, we have a rollout plan T246371, so both access methods should work simultaneously. After the transition is completed, all the special site configuration for jobrunner can be cleaned up, since both special /rpc job running scripts will be deleted.