test: simplify tcp_ref2b
test: simplify tcp_ref2b

Said test doesn't need its own close callback, it can piggyback on the
common close callback.

unknownbrackets/maxcso,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,unknownbrackets/maxcso,unknownbrackets/maxcso