"Schedule changed" check should be removed

[stephenharris]

Checks on whether the schedule routine have changed (source are causing events created via Duplicate Post not to have dates created until they're updated (reported).

These checks are designed to prevent the plug-in from removing an occurrence only to add it back in again (and so changing the ID). This is no longer necessary as per https://github.com/stephenharris/Event-Organiser/blob/2.11.1/includes/event.php#L349-L357. So these checks are superfluous and should be removed.