Pool index can not be used like this for distance evaluation

!252 (merged) replaced session index by pool index:

- frame_support::storage::storage_prefix(b"Session", b"CurrentIndex").to_vec(),
+ frame_support::storage::storage_prefix(b"Distance", b"CurrentPoolIndex").to_vec(),

But the first one is incremental while the second is modulo 3.

Therefore the files produced by the distance oracle are named "1", "2", and "3" in a loop. This won't work properly.