adapt ci to neutron making linux bridge experimental

[sean mooney]

tl;dr neutron now considers linuxbridge which uses to be the default mech driver in docs to be experimental and it is now guarded by a config flag.
we do not set it in our jobs that have the mech driver loaded but not used so neutron fails to start.

recently i noticed that gate jobs were failing with

+ functions-common:test_with_retry:2384 : timeout 60 sh -c 'while ! wget --no-proxy -q -O- http://10.209.98.53:19696; do sleep 0.5; done'
+ functions-common:test_with_retry:2385 : die 2385 'Neutron did not start'

dining into this a little more we see

Jul 06 16:21:46.635396 ubuntu-focal-rax-ord-0030301377 neutron-server[90491]: INFO neutron.plugins.ml2.managers [-] Configured mechanism driver names: ['openvswitch', 'linuxbridge']

Jul 06 16:21:46.640517 ubuntu-focal-rax-ord-0030301377 neutron-server[90491]: ERROR neutron.common.experimental [-] Feature 'linuxbridge' is experimental and has to be explicitly enabled in 'cfg.CONF.experimental'

the nova-ovs-hybrid-plug and nova-next jobs both enable the linuxbridge mech driver but don't actually use it since they only deploy ovs.

https://github.com/openstack/nova/blob/512fbdfa9933f2e9b48bcded537ffb394979b24b/.zuul.yaml#L138=
https://github.com/openstack/nova/blob/512fbdfa9933f2e9b48bcded537ffb394979b24b/.zuul.yaml#L394=

7 days ago
https://github.com/openstack/neutron/commit/7f0413c84c4515cd2fae31d823613c4d7ea43110
merged moving linux bridge to experimental

so all jobs that have it enabled either need to remove it form the mech drivers list or enable it in the config via the new option.

for nova-next and nova-ovs-hybrid-plug we can just remove the driver form the list for os-vif
the os-vif-linuxbridge need to enable it via the new config option

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/nova/+/848948

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/os-vif/+/848949

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/os-vif/+/848949
Committed: https://opendev.org/openstack/os-vif/commit/771dfffcd90dcd7c8c95c41744092f5ad4917be3
Submitter: "Zuul (22348)"
Branch: master

commit 771dfffcd90dcd7c8c95c41744092f5ad4917be3
Author: Sean Mooney <email address hidden>
Date: Thu Jul 7 12:52:41 2022 +0100

    update ci since linuxbridge is now experimental

    neutron now considers linuxbridge to be experimental
    This change enables the linuxbridge feature in the
    linuxbridge job. we do not currently declare the
    linuxbridge os-vif plug as experimental as it has
    been stable for many release and we do not have an
    experimental concept in os-vif.

    Change-Id: Ia275d1c3a9a9cf63238cf354c8e7d93ed59097a2
    Closes-Bug: #1980948

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/848948
Committed: https://opendev.org/openstack/nova/commit/cbf9b2b8739453e07fd3ca9724559a6eaa4332f6
Submitter: "Zuul (22348)"
Branch: master

commit cbf9b2b8739453e07fd3ca9724559a6eaa4332f6
Author: Sean Mooney <email address hidden>
Date: Thu Jul 7 12:46:32 2022 +0100

    update nova-next and nova-ovs-hybrid-plug to disable linuxbridge

    neutron now declares linuxbridge experimental and requires
    it to be enabled by a new config option. We do not set
    that in these jobs so the neutron server fails to load
    since we enable the linux bridge mech driver.

    we do not actully use linuxbridge in these jobs so this patch
    just disables the mech driver.

    Change-Id: I129a850c3327498d26d899c7709f5749622afdd8
    Closes-Bug: #1980948

[sean mooney (sean-k-mooney)]

neutron also has this same problem but i guess it does not use the linux bridge job in its gate.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/850025

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/850025
Committed: https://opendev.org/openstack/neutron/commit/c5807cbcf5aca795d4c2eac3a15136bd3ad96986
Submitter: "Zuul (22348)"
Branch: master

commit c5807cbcf5aca795d4c2eac3a15136bd3ad96986
Author: Sean Mooney <email address hidden>
Date: Fri Jul 15 16:33:09 2022 +0100

    update neutron-linuxbridge-tempest for bug 1980948

    change Ib18efa3f472736b58c8967847b1061da0e3897d7
    made linuxbridge an experimental feature but
    it did not enable linuxbridge in the linuxbridge jobs

    this job is used by both nova and devstack and perhaps
    other project on an as needed basis. As a result
    this is causing gate failures in neutron when some files
    are modifed such as the netwroking module or vif.py files

    This change enabled linux brdige in the base linux bridge
    job and removes an old duplicate job defintion since
    nova and devstack now use the new name.

    Change-Id: I290027fbac47bd1df7bcdd08c405db107ed63db0
    Closes-Bug: #1980948

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/os-vif 3.0.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 21.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 26.0.0.0rc1 release candidate.