Revert "Update nested-virt testing for the 2023.1 cycle"

This reverts commit f0d7d3ee057a8a95c48cf8c343474fe96233bb5d.

Reason for revert: vexxhost node provider is having issues with
jammy nodes as guest vms are not booting on 40% of scenario jobs and leading to failures as mentioned in #1999249.
Also guest vms started to take too much memory(1GiB+) in jammy[1] so it's not possible to run multiple guests vms together like we do in our tests. Using swap makes vm boot too slow(200+ sec) on those systems and without swap it just ooom-kills.

Until vexxhost node provider supports jammy hosts or we are
able to run our tests in non nested-virt providers[2] reverting
this switch, may need some job splits or ideally fixing [1] in nova
or by some global libvirt/qemu config[3].

[1] https://bugs.launchpad.net/nova/+bug/1949606
[2] https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/867934
[3] https://listman.redhat.com/archives/libvirt-users/2022-December/013844.html

Change-Id: Iad827b4bd04534bf19e189cebb2839ebe4d3837e
Related-Bug: #1999249
5 files changed