Comment 4 for bug 1962306

Reviewed: https://review.opendev.org/c/openstack/neutron/+/831214
Committed: https://opendev.org/openstack/neutron/commit/820b2e26658a3fb5e00a7cedbdc2418d2196aa42
Submitter: "Zuul (22348)"
Branch: master

commit 820b2e26658a3fb5e00a7cedbdc2418d2196aa42
Author: yatinkarel <email address hidden>
Date: Mon Feb 28 18:54:26 2022 +0530

    Ensure gateway is set for prefix delegated subnets

    With [1] gateway is no longer set for subnet created
    with prefix delegation, but when adding the subnet
    to the router it fails as it expects gateway to be
    set.

    This patch ensures gateway is set temporary to the first IP
    of the subnet as it used to be just like the temporary CIDR.
    Also need to ensure dhcp configuration is skipped to avoid the
    original issue[2].

    [1] https://review.opendev.org/c/openstack/neutron/+/699465
    [2] https://bugs.launchpad.net/neutron/+bug/1856675

    Closes-Bug: #1962306
    Related-Bug: #1856675
    Change-Id: I512f7d98ac99bb0ef06fd2acba09482e3436d18d