When attempting to disable Allow ‘Run now’ for scheduled tasks within config.php I am unable to do so sucessfully.

Not entirely sure what the shortname for this would be, however, I've tried a few variations of $CFG->enablerunnow = false; but non seem to work.

There is no config-dist.php entry for this either.

There is a reference in MDL-55980 to being able to disable this in config but no further information on how to do this.