Setting individual permissions is deprecated, charm should create and assign a Role to the nagios user

[Giuseppe Petralia]

Charm creates a nagios user to be used by nrpe checks and assigns to hit the following permissions:

    g.user_permissions_set(
        NAGIOS_USERNAME,
        [
            "users:tokenlist",
            "users:tokencreate",
            "indexercluster:read",
            "indices:failures",
            "notifications:read",
            "journal:read",
        ],
    )

But user permissions are deprecated and it should use role instead.

When you click on nagios user on Graylog Web UI you get an error message:
 “Setting individual permissions is deprecated, please consider migrating to roles instead”