Except test_subnet, there are no more object tests that would require
the plugin configured, so let's not go through the hassle of setting it
up. (For the record, this setup was not needed since
If1252c42c49cd59dba7ec7c02c9b887fdc169f51).
Change-Id: Iafb886c17dbf9a91a3514b0caa1bcd14093a796c