Auto merge of #100606 - cuviper:upgrade-linux-ci, r=Mark-Simulacrum

ci: Upgrade non-dist Linux testers from ubuntu:16.04 to 22.04

The main goal of updating to 22.04 is to get away from `llvm.allow-old-toolchain`.
A side benefit is that they can also use the system `cmake` instead of building one.

Author: bors