The [AGENT] veth_mtu parameter is no longer used

[Takashi Kajinami]

Since the [ovs] use_veth_interconnection parameter was removed by [1],
the [AGENT] veth_mtu parameter is no longer used.

[1] https://review.opendev.org/c/openstack/neutron/+/759947

We should deprecate and remove the parameter since it has no effect now.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/824446

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/824446
Committed: https://opendev.org/openstack/neutron/commit/930ec1eca3356cc4e003b5f044b6f7ca65a0bca4
Submitter: "Zuul (22348)"
Branch: master

commit 930ec1eca3356cc4e003b5f044b6f7ca65a0bca4
Author: Takashi Kajinami <email address hidden>
Date: Wed Jan 12 23:40:01 2022 +0900

    ml2 ovs: Deprecate unused [agent] veth_mtu

    The [agent] veth_mtu parameter has had unused since the [ovs]
    use_veth_interconnection parameter was removed by [1] during Wallaby.

    [1] https://review.opendev.org/c/openstack/neutron/+/759947

    This change formally deprecate the parameter so that we can remove it
    in a next cycle.

    Change-Id: Ib85959fbc06928a49df7ea104eae3aca3f04e091
    Closes-Bug: #1957180

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 20.0.0.0rc1 release candidate.