Comment 2 for bug 2044298

I'm also seeing a failure to establish the `vault:certificates` relation as a CMR:
```
unit-vault-29: 17:59:16 WARNING unit.vault/29.certificates-relation-created hvac.exceptions.InvalidPath: no handler for route 'charm-pki-local/cert/ca_chain', on get http://127.0.0.1:8220/v1/charm-pki-local/cert/ca_chain
unit-vault-29: 17:59:16 ERROR juju.worker.uniter.operation hook "certificates-relation-created" (via explicit, bespoke hook script) failed: exit status 1
unit-vault-29: 17:59:58 ERROR unit.vault/29.juju-log certificates:165: Unable to find implementation for relation: peers of vault-ha
unit-vault-29: 17:59:59 ERROR unit.vault/29.juju-log certificates:165: Hook error:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/charms/reactive/__init__.py", line 74, in main
    bus.dispatch(restricted=restricted_mode)
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 390, in dispatch
    _invoke(other_handlers)
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 359, in _invoke
    handler.invoke()
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 181, in invoke
    self._action(*args)
  File "/var/lib/juju/agents/unit-vault-29/charm/reactive/vault_handlers.py", line 1055, in publish_ca_info
    chain = vault_pki.get_chain()
  File "/var/lib/juju/agents/unit-vault-29/charm/lib/charm/vault_pki.py", line 86, in get_chain
    response = client.secrets.pki.read_certificate('ca_chain',
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/hvac/api/secrets_engines/pki.py", line 76, in read_certificate
    return self._adapter.get(
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/hvac/adapters.py", line 113, in get
    return self.request("get", url, **kwargs)
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/hvac/adapters.py", line 364, in request
    response = super(JSONAdapter, self).request(*args, **kwargs)
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/hvac/adapters.py", line 330, in request
    utils.raise_for_error(
  File "/var/lib/juju/agents/unit-vault-29/.venv/lib/python3.10/site-packages/hvac/utils.py", line 43, in raise_for_error
    raise exceptions.InvalidPath(message, errors=errors, method=method, url=url)
hvac.exceptions.InvalidPath: no handler for route 'charm-pki-local/cert/ca_chain', on get http://127.0.0.1:8220/v1/charm-pki-local/cert/ca_chain
```

I'm running the following:

```
juju deploy ovn-central ovn-central --model lxd-cloud/cell0-ovn-central --channel 23.03/stable --num-units 3
juju deploy postgresql postgresql --model lxd-cloud/cell0-ovn-central --channel latest/stable --num-units 1
juju deploy vault vault --model lxd-cloud/cell0-ovn-central --config auto-generate-root-ca-cert=true --config totally-unsecure-auto-unlock=true --channel 1.8/stable --num-units 1

while ! juju status -m lxd-cloud/cell0-ovn-central | grep vault/ | grep -q "Unit is ready" ; do
  sleep 2
done

sleep 200

juju integrate ovn-central:certificates vault:certificates --model lxd-cloud/cell0-ovn-central

while ! juju status -m lxd-cloud/cell0-ovn-central | grep vault/ | grep -q "Unit is ready" ; do
  sleep 2
done

sleep 200

juju integrate vault:db postgresql:db --model lxd-cloud/cell0-ovn-central

sleep 600

juju integrate lxd-cloud/cloud-rack0.cloud-rack0-ovn-dedicated-chassis vault --model lxd-cloud/cell0-ovn-central
```