The vm-switch experiment for VM-to-VM networking via vhost-user-net
didn't work out — it performs poorly under load, with busy connections
saturating the buffer and causing high latency for others.
Removes the vm-switch Rust crate, bufferbloat-test suite, all NixOS
module integration (options, services, networking, assertions, scripts),
and documentation.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>