Fix test_server_clear_stale_data (#2748)
Fix test_server_clear_stale_data (#2748)

This test sometime fails in CI, I'm not sure why yet. But I think it may relate
to the CF_RAFT, because CF_RAFT is writting while the test constructing the
necessary SST files. So I remove the CF_RAFT and CF_WRITE (so we don't need to
care about the SliceTransform).
pingcap/tikv,BusyJay/tikv,BusyJay/tikv,BusyJay/tikv,c4pt0r/tikv,pingcap/tikv,BusyJay/tikv