upgrade: refactor single-hop fs tests
upgrade: add double-hop bobtail -> cuttlefish -> next fs tests
upgrade/fs: make single hop cuttlefish -> next (not bobtail -> next)

The bobtail ceph-fuse is buggy and these tests keep failing e.g. on umount,
but we don't really care about fixing the bobtail fs bugs.
upgrade/rados: refactor, expand matrix, start with cuttlefish
upgrade: add rados-double suite (bobtail -> cuttlefish -> next)
Revert "upgrade: add double-hop bobtail -> cuttlefish -> next fs tests"

This reverts commit fbdb7774bb381ff1426650c47cdb36282c4c77d2.

We don't care about bobtail fs.