gh-155852: Do not cancel remaining Executor.map calls on a callable's TimeoutError (GH-155853)

A TimeoutError raised by the mapped callable was re-raised like the
map(timeout=...) wait timeout, aborting the iteration and cancelling the
remaining calls, unlike every other exception since gh-108518. A wait timeout
only occurs while the future is still running, so a TimeoutError from an
already-finished future is treated as the callable's own result.