Increase tolerance in update scripts for more stable playlists

[loucasal]

Issue: some channels are frequently added and removed from playlists, sometimes even multiple times per week. As a result, edits applied downstream (e.g. regrouping, adding to favourites, etc.) are undone at every such update.

As a user, I would appreciate having more stable playlists, even if it slightly increases the risk of encountering a non-working link.
There are probably several ways to achieve this - the most obvious would be to require multiple consistent status results before excluding a channel.