Fix unwanted snapshots at 04:15

From iXsystems community: https://www.ixsystems.com/community/threads/unexpected-automatic-daily-snapshots.81986/

I had custom snapshot tasks on all of my datasets to create a daily snapshot at 23:00.

After the upgrade to 11.3 i decided to change them to the standard daily task that runs at 00:00.

Ever since the change i see the expected snapshots at 00:00 but another at 04:15 for every dataset.
I've tried deleteing the scheduled task but the snapshot at 04:15 is still created.

Anyone have an idea how i can stop these additional snapshots being created?

PR: https://github.com/freenas/freenas/pull/4179