Merge branch 'selftests-vsock-refactor-and-improve-vmtest-infrastructure'

Bobby Eshleman says:

====================
selftests/vsock: refactor and improve vmtest infrastructure

This patch series refactors the vsock selftest VM infrastructure to
improve test run times, improve logging, and prepare for future tests
which make heavy usage of these refactored functions and have new
requirements such as simultaneous QEMU processes.
====================

Link: https://patch.msgid.link/20251108-vsock-selftests-fixes-and-improvements-v4-0-d5e8d6c87289@meta.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>