Remove Python 2 testing and gate jobs

[Brian Rosmaita]

With the Ussuri release, OpenStack will no longer support Python 2.

We need to remove Python 2 testing right away, because as other project and libraries remove Python 2 support, our testing and gate jobs may break. (See, for example, the discussion on https://review.opendev.org/#/c/695007/ )

The periodic "tips" jobs will definitely break.

Need to remove the py2* testenvs in tox as well as py2-specific testing configured in .zuul.yaml

As part of this, should make sure we are configured to test the official Ussuri python runtimes, namely, py36 and py37. See https://governance.openstack.org/tc/reference/runtimes/ussuri.html

[Brian Rosmaita (brian-rosmaita)]

I submitted the Glance patch before writing up the bug:

https://review.opendev.org/#/c/695707/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/695707
Committed: https://git.openstack.org/cgit/openstack/glance/commit/?id=40bd312410d6ff23ea5d8b6d6263f40bd456fffd
Submitter: Zuul
Branch: master

commit 40bd312410d6ff23ea5d8b6d6263f40bd456fffd
Author: Brian Rosmaita <email address hidden>
Date: Fri Nov 22 10:11:52 2019 -0500

    Remove py2 testing, jobs

    Change tox.ini so that all jobs are python3, and add explicit
    unit/functional testenvs for the two ussuri python runtimes
    (3.6 and 3.7).

    Remove py2 jobs from .zuul.yaml and redefine the periodic "tips"
    jobs so that they are testing with the ussuri python runtimes.
    Added nodeset: ubuntu-bionic to the abstract base jobs so that
    py3.7 is available.

    Co-authored-by: Ghanshyam Mann <email address hidden>
    Co-authored-by: Brian Rosmaita <email address hidden>

    Closes-bug: #1853693
    Change-Id: I15467c34fc8466fa1724c5401dc879ae77c1922d

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/glance 20.0.0.0b1 development milestone.

[Cyril Roelandt (cyril-roelandt)]

This was fixed in glance_store with 3bf4d29a0f2d38916bb20b287b7ee486b09613e0 .

[Cyril Roelandt (cyril-roelandt)]

This was fixed in python-glanceclient with a4465dfc2268b2fc36f04a1a7e5455f6f8c92886 .