Confusing error message of create-resources action when required security groups are not found

[Przemyslaw Hausman]

Running configure-resources action fails with message "('neutron', 'security_groups')". The message is quite cryptic and does not tell what the problem is.

Steps to reproduce:
1. Do not tag required security groups [1] with charm-octavia or charm-octavia-health
2. Run 'juju run-action --wait octavia/leader configure-resources'

Action fails with message: ('neutron', 'security_groups').

Expected behavior:
Action fails with message e.g.: 'Required security groups were not found. Create Amphora Security Group tagged with "charm-octavia" and Controller Security Group tagged with "charm-octavia-health"'

[1] https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-octavia.html#resource-configuration