ngtcp2: stabilize recv

ngtcp2: stabilize recv

When receiving on a stream that already failed or has already been closed,
return the matching error code without touching the connection. In case
the connection shows errors, e.g. the server closed, those errors should
not have impact on an already failed/closed stream.

This might mitigate flakiness in pytest 07_13 where unexpected errors
occur after a successful upload.

Closes #20220