gh-91487: Optimize asyncio UDP speed (GH-91488)

Fix #91487

When transferring a small file, e.g. 256 KiB, the speed of this PR is comparable. However, if a large file, e.g. 65536 KiB, is transferred, asyncio UDP will be over 100 times faster than the original. The speed is presumably significantly faster if a larger file is transferred, e.g. 1048576 KiB.

Automerge-Triggered-By: GH:gpshead