Avoid FT errors caused by other projects change
Avoid FT errors caused by other projects change

Zuul FT has failed by multiple reasons,
  A: devstack changes default ML2 Driver to OVN.
  B: kuryr-kubernetes changes to use kubeadm.

This patch is just workaround for FT errors caused by above changes.
The formal fixes will be done separately.

[About A: devstack change]
Zuul FT has failed to build the environment with the following error:
'The q-agt/neutron-agt service must be disabled with OVN.'

The FT error is caused by a merged devstack patch [1],
[1] https://review.opendev.org/c/openstack/devstack/+/791436

This patch temporarily set ML2 driver to `openvswitch` that was used as
default value before merging [1] patch.

[About B: kuryr-kubernetes change]
Some nodes using the kuryr-kubernetes service will fail to build with
the error shown in the bug report [2].
[2] https://bugs.launchpad.net/bugs/1930368

Above error seems to be occured by kuryr-kubernetes patch [3] that
changes to use kubeadm for installing Kubernetes on devstack.
[3] https://review.opendev.org/c/openstack/kuryr-kubernetes/+/779250

This patch temporarily use kuryr-kubernetes stable/wallaby branch
for resolving FT error.

Change-Id: I7742c30ed6cb910d58183c18e859acac244ff3ae

openstack/tacker,openstack/tacker,stackforge/tacker,stackforge/tacker,openstack/tacker