tests: Updating the tests to use Ubuntu 22.04 docker image

As of https://gem5-review.googlesource.com/c/public/gem5/+/64177 we
support version 22.04. This patch therefore updates the testing
infrastructure (kokoro/quick, nightly/long, weekly/extra-long) to use
the Ubuntu 22.04 docker image.

The "jenkins/gem5art-tests.sh" test script has been updated to no longer
require the `pip upgrade`. This was needed for Ubuntu 20.04 as it
utilized an older version of pip which did not have all the dependencies
these tests requried. As of Ubuntu 20.04 this is no longer required.

Change-Id: Ia8f8b1b2c62ad5d5a8419cb31b6a1d2b6dff7ac9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/64291
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
4 files changed