Add packages for Ubuntu 22.04

The planned release date for Ubuntu 22.04, was April 21, 2022. This is an LTS release, and so we may be able to start seeing production servers switching to this version in the coming months.

Our packagecloud server already has support for 22.04 packages, so we should look to add Ubuntu 22.04 support to GitLab for the May 22nd GitLab release.

cf. #5176 (closed)

Edited Apr 25, 2022 by Takuya Noguchi