stream: fix Transform with hwm 0 regression
This undoes a patch from #40947, and reworks it to continue handling backpressure when highWaterMark: 0
, as described in https://github.com/nodejs/node/issues/42457#issuecomment-1172157557.
The new test fails on node releases with the patch from #40947, like v16.4, and passes on node v14 and node v16.3 from before it was introduced. It is also designed, so that it will fail if highWaterMark: 1
is set instead.