Close down IRC
Description
Close down the IRC channel and remove the client integration.
Rationale
Nobody uses the channel anymore and most of the communication takes place via discord (or gitlab and the forums).
Additional Information
How to leave the irc channel and how to turn off the annoying channel join and part messages are some of the most frequent questions asked by new players. As no one even uses IRC anymore, you might as well get rid of the feature and avoid those annoyances.