Fix #1551: mgmt_auth_token breaking the node_setup of monitor (fix) (#1552)
Fix #1551: mgmt_auth_token breaking the node_setup of monitor (fix) (#1552)

this commit was broken cause using `get('auth_token', default=None)`
`dict.get` doesn't have named arguments.

```
    commit cdbd3fdb9e8e856a681fedcbffd361fe7032b116 (HEAD -> fix_1546_2, upstream/master)

    Fix #1546: mgmt_auth_token breaking the node_setup of monitor (#1551)

    was introduced by #1542
```
scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-longevity-tests