Upgrade to Buster 10.3

Originally created by @intrigeri on #17458 (Redmine)

It is scheduled for Saturday, February 8th, 2020.

Feature Branch: bugfix/17458-buster-10.3+force-all-tests

Edited May 15, 2020 by intrigeri

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information