Revert "add patch to work around stuck guest IO with iothread and VirtIO block/SCSI"

Revert "add patch to work around stuck guest IO with iothread and VirtIO block/SCSI"

This reverts commit 6b7c1815e1c89cb66ff48fbba6da69fe6d254630.

The attempted fix has been reported to cause high CPU usage after
backup [0]. Not difficult to reproduce and it's iothreads getting
stuck in a loop. Downgrading to pve-qemu-kvm=8.1.2-4 helps which was
also verified by Christian, thanks! The issue this was supposed to fix
is much rarer, so revert for now, while upstream is still working on a
proper fix.

[0]: https://forum.proxmox.com/threads/138140/

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>