The q-agt/neutron-agt service must be disabled with OVN

[willzhang]

I want install two nodes devstack cluster with controller and compute.

OS: ubuntu 22.04
controller node local.conf
```
[[local|localrc]]
HOST_IP=192.168.72.33
ADMIN_PASSWORD=secret
DATABASE_PASSWORD=$ADMIN_PASSWORD
RABBIT_PASSWORD=$ADMIN_PASSWORD
SERVICE_PASSWORD=$ADMIN_PASSWORD
DEST=/opt/stack
## Neutron options
FLOATING_RANGE=192.168.72.0/24
Q_FLOATING_ALLOCATION_POOL=start=192.168.72.220,end=192.168.72.230
PUBLIC_INTERFACE=ens33
PUBLIC_NETWORK_GATEWAY=192.168.72.8

```
compute node local.conf
```
[[local|localrc]]

DEST=/opt/stack/
LOGDIR=$DEST/logs
LOGFILE=$LOGDIR/stack.sh.log
FORCE=yes

ADMIN_PASSWORD=secret
DATABASE_PASSWORD=secret
RABBIT_PASSWORD=secret
SERVICE_PASSWORD=secret

HOST_IP=192.168.72.40
SERVICE_HOST=192.168.72.33
MYSQL_HOST=192.168.72.40
RABBIT_HOST=192.168.72.40
GLANCE_HOSTPORT=192.168.72.40:9292

## Neutron options
PUBLIC_INTERFACE=ens33
ENABLED_SERVICES=n-cpu,rabbit,q-agt,placement-client
```

Follw the docs: https://docs.openstack.org/devstack/latest/guides/neutron.html

The host devstack-2 has a very minimal local.conf.
```
[[local|localrc]]
HOST_IP=172.18.161.7
SERVICE_HOST=172.18.161.6
MYSQL_HOST=172.18.161.6
RABBIT_HOST=172.18.161.6
GLANCE_HOSTPORT=172.18.161.6:9292
ADMIN_PASSWORD=secret
MYSQL_PASSWORD=secret
RABBIT_PASSWORD=secret
SERVICE_PASSWORD=secret

## Neutron options
PUBLIC_INTERFACE=eth0
ENABLED_SERVICES=n-cpu,rabbit,q-agt,placement-client
```
Network traffic from eth0 on the compute nodes is then NAT’d by the controller node that runs Neutron’s neutron-l3-agent and provides L3 connectivity.

ERROR LOGS
```
2024-03-07 01:43:30.287 | +inc/python:pip_install:222 result=0
2024-03-07 01:43:30.296 | +inc/python:pip_install:224 time_stop pip_install
2024-03-07 01:43:30.304 | +functions-common:time_stop:2421 local name
2024-03-07 01:43:30.313 | +functions-common:time_stop:2422 local end_time
2024-03-07 01:43:30.322 | +functions-common:time_stop:2423 local elapsed_time
2024-03-07 01:43:30.332 | +functions-common:time_stop:2424 local total
2024-03-07 01:43:30.341 | +functions-common:time_stop:2425 local start_time
2024-03-07 01:43:30.349 | +functions-common:time_stop:2427 name=pip_install
2024-03-07 01:43:30.360 | +functions-common:time_stop:2428 start_time=1709775762302
2024-03-07 01:43:30.369 | +functions-common:time_stop:2430 [[ -z 1709775762302 ]]
2024-03-07 01:43:30.378 | ++functions-common:time_stop:2433 date +%s%3N
2024-03-07 01:43:30.388 | +functions-common:time_stop:2433 end_time=1709775810380
2024-03-07 01:43:30.397 | +functions-common:time_stop:2434 elapsed_time=48078
2024-03-07 01:43:30.407 | +functions-common:time_stop:2435 total=45765
2024-03-07 01:43:30.416 | +functions-common:time_stop:2437 _TIME_START[$name]=
2024-03-07 01:43:30.424 | +functions-common:time_stop:2438 _TIME_TOTAL[$name]=93843
2024-03-07 01:43:30.433 | +inc/python:pip_install:225 return 0
2024-03-07 01:43:30.443 | +inc/python:setup_package:473 [[ -e == \-\e ]]
2024-03-07 01:43:30.455 | +inc/python:setup_package:473 [[ True == \F\a\l\s\e ]]
2024-03-07 01:43:30.464 | +inc/python:_setup_package_with_constraints_edit:419 use_library_from_git /opt/stack/neutron
2024-03-07 01:43:30.476 | +inc/python:use_library_from_git:272 local name=/opt/stack/neutron
2024-03-07 01:43:30.485 | +inc/python:use_library_from_git:273 local enabled=1
2024-03-07 01:43:30.494 | +inc/python:use_library_from_git:274 [[ '' = \A\L\L ]]
2024-03-07 01:43:30.503 | +inc/python:use_library_from_git:274 [[ ,, =~ ,/opt/stack/neutron, ]]
2024-03-07 01:43:30.513 | +inc/python:use_library_from_git:275 return 1
2024-03-07 01:43:30.528 | +lib/neutron:install_neutron:550 [[ ovn == \o\v\n ]]
2024-03-07 01:43:30.539 | +lib/neutron:install_neutron:551 install_ovn
2024-03-07 01:43:30.549 | +lib/neutron_plugins/ovn_agent:install_ovn:370 echo 'Installing OVN and dependent packages'
2024-03-07 01:43:30.549 | Installing OVN and dependent packages
2024-03-07 01:43:30.558 | +lib/neutron_plugins/ovn_agent:install_ovn:373 ovn_sanity_check
2024-03-07 01:43:30.568 | +lib/neutron_plugins/ovn_agent:ovn_sanity_check:357 is_service_enabled q-agt neutron-agent
2024-03-07 01:43:30.614 | +functions-common:is_service_enabled:2077 return 0
2024-03-07 01:43:30.623 | +lib/neutron_plugins/ovn_agent:ovn_sanity_check:358 die 358 'The q-agt/neutron-agt service must be disabled with OVN.'
2024-03-07 01:43:30.632 | +functions-common:die:285 local exitcode=0
2024-03-07 01:43:30.640 | [Call Trace]
2024-03-07 01:43:30.641 | ./stack.sh:979:stack_install_service
2024-03-07 01:43:30.641 | /opt/stack/devstack/lib/stack:32:install_neutron
2024-03-07 01:43:30.641 | /opt/stack/devstack/lib/neutron:551:install_ovn
2024-03-07 01:43:30.641 | /opt/stack/devstack/lib/neutron_plugins/ovn_agent:373:ovn_sanity_check
2024-03-07 01:43:30.641 | /opt/stack/devstack/lib/neutron_plugins/ovn_agent:358:die
2024-03-07 01:43:30.645 | [ERROR] /opt/stack/devstack/lib/neutron_plugins/ovn_agent:358 The q-agt/neutron-agt service must be disabled with OVN.
2024-03-07 01:43:31.649 | Error on exit
```