Clear scheduled jobs on edition publish

if an editor chooses to immediately publish a scheduled edition, we should clear the scheduled sidekiq job. missed this earlier when we implemented scheduling.

also includes a minor readability fix.
`ScheduledPublisher`, which is used for publishing a scheduled edition, doesn't use the `EditionProgressor#progress` to publish an edition, but uses `Edition#publish_anonymously`. hence, the job won't try to cancel itself when scheduled publishing triggers a `publish`.