frr config is not compatible with 8.0

[Michele Baldessari]

While testing frr, it seems that one of our ACLs is not accepted by frr 8.0:
2021/08/09 14:18:23 BGP: [JMR52-70SM0][EC 100663332] error processing configuration change: error [validation] event [validate] operation [modify] xpath [/frr-filter:lib/prefix-list[type='ipv4'][name='only-default-host-prefixes']/entry[sequence='5']/ipv4-prefix] message: duplicated prefix list value: 0.0.0.0/0

This is because ip prefix-list only-default-host-prefixes permit 0.0.0.0/0 seems to not be parsed by frr 8.0 any longer. Potentially due to https://github.com/FRRouting/frr/commit/bf79e923167c79b2e813b7e7efda7211949d6378

While we think this is an frr bug (our frr version config is explicitly set to 7.0) and we'll chase upstream on this, let's make this config compatible with both frr versions.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/tripleo-ansible/+/803972

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Michele Baldessari <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/tripleo-ansible/+/803972
Reason: frr upstream recognized the bug and has a fix lined up which we tested, let's just drop this