Another variant seen:- 
https://storage.bhs.cloud.ovh.net/v1/AUTH_dcaab5e32b234d56b626f72581e3644c/zuul_opendev_logs_b51/914260/2/gate/neutron-tempest-plugin-openvswitch-enforce-scope-old-defaults/b51575b/testr_results.html

DHCP request:-
Apr 15 10:32:46.217414 np0037286317 dnsmasq-dhcp[104433]: DHCPDISCOVER(tap6978d05e-c0) fa:16:3e:fb:c4:fa
Apr 15 10:32:46.217428 np0037286317 dnsmasq-dhcp[104433]: DHCPOFFER(tap6978d05e-c0) 10.1.0.11 fa:16:3e:fb:c4:fa
Apr 15 10:32:46.218501 np0037286317 dnsmasq-dhcp[104433]: DHCPREQUEST(tap6978d05e-c0) 10.1.0.11 fa:16:3e:fb:c4:fa
Apr 15 10:32:46.218515 np0037286317 dnsmasq-dhcp[104433]: DHCPACK(tap6978d05e-c0) 10.1.0.11 fa:16:3e:fb:c4:fa tempest-internal-dns-test-vm-1365155710


Metadata request:-
Apr 15 10:33:10.806011 np0037286317 neutron-metadata-agent[60802]: INFO eventlet.wsgi.server [-] ::ffff:10.1.0.11,<local> "GET /2009-04-04/meta-data/public-keys/0/openssh-key HTTP/1.1" status: 200  len: 341 time: 0.0893147

firth ssh attempt:-
2024-04-15 10:32:48,931 85216 INFO     [tempest.lib.common.ssh] Creating ssh connection to '172.24.5.45:22' as 'cirros' with public key authentication
2024-04-15 10:32:50,538 85216 INFO     [paramiko.transport] Connected (version 2.0, client dropbear_2020.81)
2024-04-15 10:32:50,598 85216 INFO     [paramiko.transport] Authentication (publickey) failed.
Last ssh attempt:-
2024-04-15 10:46:12,508 85216 ERROR    [tempest.lib.common.ssh] Failed to establish authenticated ssh connection to cirros@172.24.5.45 after 38 attempts. Proxy client: no proxy client

Even after keys injected, why ssh still fails? i recall reading some bug report related to this but can't find it, any one recall and know that issue?

Another variant:-
https://a2cd5747e9df40c0c253-4cf4bb096d4774f141f32d30757edf40.ssl.cf5.rackcdn.com/915467/1/check/neutron-tempest-plugin-openvswitch-enforce-scope-old-defaults/b6aae17/testr_results.html
https://fe84552b8a9ac6c570c5-2c52d5c43a05db941913513785ce0245.ssl.cf2.rackcdn.com/916603/1/gate/neutron-tempest-plugin-openvswitch/d4e5c7d/testr_results.html

test: test_qos
cirros console:-
Apr 11 18:27:44 cirros daemon.info dhcpcd[250]: eth0: soliciting a DHCP lease
Apr 11 18:27:49 cirros daemon.info dhcpcd[250]: eth0: probing for an IPv4LL address
Apr 11 18:27:54 cirros daemon.info dhcpcd[250]: eth0: using IPv4LL address 169.254.219.22

No DHCP request seen in dhcp agent logs

Another variant:-
https://a2cd5747e9df40c0c253-4cf4bb096d4774f141f32d30757edf40.ssl.cf5.rackcdn.com/915467/1/check/neutron-tempest-plugin-openvswitch-enforce-scope-old-defaults/b6aae17/testr_results.html

test:- test_reuse_ip_address_with_other_fip_on_other_router
Apr 11 17:30:10.163365 np0037266354 dnsmasq-dhcp[101823]: DHCPDISCOVER(tapb4f76e0b-f9) fa:16:3e:45:f4:61
Apr 11 17:30:10.163389 np0037266354 dnsmasq-dhcp[101823]: DHCPOFFER(tapb4f76e0b-f9) 10.1.0.14 fa:16:3e:45:f4:61
Apr 11 17:30:10.164179 np0037266354 dnsmasq-dhcp[101823]: DHCPREQUEST(tapb4f76e0b-f9) 10.1.0.14 fa:16:3e:45:f4:61
Apr 11 17:30:10.164193 np0037266354 dnsmasq-dhcp[101823]: DHCPACK(tapb4f76e0b-f9) 10.1.0.14 fa:16:3e:45:f4:61 tempest-server-test-911756074

no metadata request seen around that, seen at later time but may be different issue
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: DEBUG neutron.agent.metadata.agent [-] Request: GET /2009-04-04/meta-data/public-keys HTTP/1.0
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: Accept: */*
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: Connection: close
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: Content-Type: text/plain
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: Host: 169.254.169.254
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: User-Agent: curl/7.84.0
Apr 11 17:41:30.677170 np0037266354 neutron-metadata-agent[61092]: X-Forwarded-For: ::ffff:10.1.0.14