CI: Move to Ubuntu 2022.04 "Jammy" for CI base

CI: Move to Ubuntu 2022.04 "Jammy" for CI base

- We now have a new enough sbsigntools in the distro, stop building.
- Use the 20220801 tag for Jammy.
- Move to pygit2 1.9.2 (current version) as the old one doesn't build on
 "Jammy".
- Add the working directory to the list of safe directories for git.
- Move to pytest 6.2.5 to address other issues.
- This move exposed a number of minor issues in the existing scripts we
  used within CI to perform the jobs themselves.  The most notable changes
  here involve using 'set +e / set -e' to enforce when we should or should
  not make non-zero buildman status be a fatal error.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>