Octavia fails in scenario010 - sometimes

Octavia fails to deploy in scenario010 jobs sporadically, for example ussuri:

https://logserver.rdoproject.org/openstack-periodic-integration-stable2/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-scenario010-standalone-ussuri/a0aa701/logs/undercloud/home/zuul/standalone_deploy.log.txt.gz

2021-03-16 05:49:37.647856 | fa163e8a-4ea8-df1d-8aff-00000000523e | TASK | Configure octavia on overcloud

Octavia playbook is stuck on playing for octavia nodes and causes timeout:

https://logserver.rdoproject.org/openstack-periodic-integration-stable2/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-scenario010-standalone-ussuri/a0aa701/logs/undercloud/home/zuul/standalone-ansible-g9uabwot/octavia-ansible/octavia-ansible.log.txt.gz

2021-03-16 05:51:13,824 p=181716 u=root n=ansible | PLAY [octavia_nodes] ***********************************************************

https://logserver.rdoproject.org/openstack-periodic-integration-stable2/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-scenario010-standalone-ussuri/a0aa701/logs/undercloud/var/log/extra/journal_errors.txt.gz

2021-03-16T05:36:19+0000 standalone.localdomain haproxy[118077]: proxy nova_osapi has no server available!
2021-03-16T05:36:20+0000 standalone.localdomain haproxy[118077]: Server octavia/standalone.ctlplane.localdomain is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
2021-03-16T05:36:20+0000 standalone.localdomain haproxy[118077]: proxy octavia has no server available!
2021-03-16T05:36:20+0000 standalone.localdomain haproxy[118077]: Server placement/standalone.ctlplane.localdomain is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 0 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.