This feature was not used in 8 years and from frontend did not even
properly work anymore and was implemented using deprecated API.
So get rid of it.
The last version that was using a changelog from the changelog server
was Nextcloud 20.
We use the firstrunwizard nowadays for informing about Nextcloud
changes in new releases.
Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>
