v10.5.2

Log send_and_clear's discarded Result in send_data (10.5.2)

10.5.1's tracing proved overlay_relay bytes ARE correctly received by
Quinn (recv.read() returns the exact byte count, loop continues
healthily) but never reach any Erlang code -- not even the catch-all
clause that already logs unexpected messages. The one thing in the
whole path never actually checked was env.send_and_clear's own Result,
previously discarded unconditionally. This logs it.

No functional change. To be reverted alongside 10.5.1's logging once
root-caused.