Deprecate and remove vlan_transparent config option

[Slawek Kaplonski]

We have config option to enable vlan_transparent api extension currently. We will also have similar config option for vlan_qinq (it is now proposed in [1]). In both cases we have validation by mechanism drivers if option is or is not supported while networks are created.
We can also filter out enabled API extensions by mechanism drivers, see [2] for example

So I think we should deprecate those config options in the E or F cycle and then remove them completely.

[1] https://review.opendev.org/c/openstack/neutron/+/937372
[2] https://github.com/openstack/neutron/blob/559672f777312d00c4358626650cc577e49ec0b6/neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py#L237

[Brian Haley (brian-haley)]

Although this wasn't tagged as an RFE, we reviewed it at the PTG and approved moving forward.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/951136

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/951136
Committed: https://opendev.org/openstack/neutron/commit/11ff4f2f981969cf56ffcafa0a2f9a8fe11eabce
Submitter: "Zuul (22348)"
Branch: master

commit 11ff4f2f981969cf56ffcafa0a2f9a8fe11eabce
Author: Slawek Kaplonski <email address hidden>
Date: Wed May 28 15:14:12 2025 +0200

    Deprecate `vlan_qinq` and `vlan_transparent` config options

    Those config knobs are now deprecated as availability of the appropriate
    API extension can be calculated based on the mech drivers loaded.
    It still can be disabled manually using deprecated config options but
    to do that it has to be explicitly set to "False".

    Additionally this patch changes default value of both those config
    options to be `None` now which means - calculate it automatically.

    Closes-bug: #2092174
    Change-Id: I3df2d3ebc8320c7df80ced25c18f5f573722b8d5

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 27.0.0.0b1 Flamingo development milestone.