Add suffix to Aardvark internal network filenames

[mheon]

Use the %int suffix for internal network files passed to AV so we can properly trigger DNS handling (or, more accurately, lack of DNS handling) over there. Also, to handle version migrations, if there is a previous file for the network named without the suffix, delete that.

This will unblock [1].

[1] https://github.com/containers/aardvark-dns/pull/447