Heavily revise this test.
Heavily revise this test.

- Simplify code
- Remove bogus leftover (tests) in the end
- Resolve deadlock that resulted from using `tcp-abandon-port' in
  `net/ftp'
- Actually there's no need for threads, probably because of small size
  of data, so keep it.
- Use scribble syntax instead of here-strings, and move the text out of
  the way.

original commit: f297c98c1a497a71353c544b2613e4146eb6060d

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket