[goal] Migrate glance_store jobs to focal
[goal] Migrate glance_store jobs to focal

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

Set bionic nodeset for py36 job and focal nodeset for rest all.

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-fo$

Change-Id: Ide3cefdcf5e99f9593890a8f9bd4c8520af12d29
Story: #2007865
Task: #40185

openstack/glance_store,openstack/glance_store