The Keystone `regenerate-password` action does not work correctly.

[Pedro Castillo]

The regenerate-password action fails saying that the admin user does not exist, even though the charm itself shows the details for the admin user using the get-admin-account action.
```
# juju run keystone/leader regenerate-password username=admin
Running operation 109 with 1 task
  - task 110 on unit-keystone-2

Waiting for task 110...
Action id 110 failed: Regeneration of password failed: User admin does not exist
```

The admin user is present in the OpenStack API.
```
# openstack user show admin
+---------------------+----------------------------------+
| Field | Value |
+---------------------+----------------------------------+
| domain_id | 846cc83fe3914eceb0f0f560b5e9aab5 |
| enabled | True |
| id | 80b19391661f4bb8bbc57522a3c4716e |
| name | admin |
| options | {} |
| password_expires_at | None |
+---------------------+----------------------------------+
```

This admin user can also be seen using the `get-admin-account` Keystone action.
```
# juju run keystone/leader get-admin-account
Running operation 115 with 1 task
  - task 116 on unit-keystone-2

Waiting for task 116...
api-version: "3"
internal-endpoint: http://10.11.8.16/openstack-keystone/v3
openrc: |
  # openrc for access to OpenStack
  export OS_AUTH_URL=http://10.11.8.18/openstack-keystone/v3
  export OS_USERNAME=admin
  export OS_PASSWORD=[REDACTED]
  export OS_PROJECT_DOMAIN_NAME=admin_domain
  export OS_USER_DOMAIN_NAME=admin_domain
  export OS_PROJECT_NAME=admin
  export OS_IDENTITY_API_VERSION=3
  export OS_AUTH_VERSION=3
password: [REDACTED]
project-domain-name: admin_domain
project-name: admin
public-endpoint: http://10.11.8.18/openstack-keystone/v3
region: PC5A-One
user-domain-name: admin_domain
username: admin
```