Tests fail on Ubuntu 22.04

Our GitHub Runners were recently updated from Ubuntu 20.04 to Ubuntu 22.04. This broke two PUT conformance tests. The error can be recreated on a fresh Ubuntu 22.04 VM.

This PR hardcoded the runners to use 20.04 so CI will pass.

These are the changes introduced with 22.04 https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2204-Readme.md

See attached logs for failed test output.

E2E failure: https://github.com/quay/quay/actions/runs/3734957067/jobs/6337627527