AST-850 Switch CI to Ubuntu 22.04
The version of GCC in Ubuntu 18.04 has incomplete C++17 support and fails to compile. Therefore switch to Ubuntu 20.04 and 22.04.
Remove some obsolete Docker images.
Since Ubuntu 22.04 has Python 3.10 a script needed to be adjusted, it expected a single minor digit.
Edited by Mark de Wever