tests: add groovy integration tests for ubuntu

[blackboxsw]

now that we've turned on jenkins CI for cloud-init. let's add the groovy release so we can test it.

without this fix our jenkins runner will see:

cloud_tests run: error: argument -n/--os-name: invalid choice: 'groovy' (choose from 'artful', 'bionic', 'centos66', 'centos70', 'cosmic', 'disco', 'eoan', 'focal', 'jessie', 'stretch', 'trusty', 'xenial')
ERROR: InvocationError: '/var/lib/jenkins/servers/server/workspace/cloud-init-integration-ec2-g/cloud-init/.tox/citest/bin/python -m tests.cloud_tests run --os-name=groovy --platform=ec2 --preserve-data --data-dir=results --verbose --deb=/var/lib/jenkins/servers/server/workspace/cloud-init-integration-ec2-g/cloud-init_20.2-2462-g0919bd4-0ubuntu1+1837~trunk~ubuntu20.10.1_all.deb'

Failure case here: https://jenkins.ubuntu.com/server/view/cloud-init,%20curtin,%20streams/job/cloud-init-integration-ec2-g/1/console

[raharper]

Looks good.