Remove legacy block help + settings from config page

[jenlampton]

This module should always provide a block. There's no reason to ask if it should on the settings page, and then hide it if not. If users don't want to use it they simply won't put it on the page.

Additionally, there is some help text telling people to position blocks via the block UI, which is not correct for Backdrop.

Let's kill these things and create a better user experience :)

[jenlampton]

this issue has been fixed in the 2.x branch