Fix sinitized bug for Junos

[minefuto]

get_config(sanitized=True) cannot remove community-name when the following configuration.

snmp {
    community public;
    community secure {
        authorization read-only;
    }
}

result:

snmp {
    community public;
    community <removed> {
        authorization read-only;
    }
}

expected:

snmp {
    community <removed>;
    community <removed> {
        authorization read-only;
    }
}

I fixed this issue.