Revert "nixos/libvirtd-service: fix for garbage collected emulator paths"

This reverts commit f52f9bf7cd922b54c874e5500a2c64277e57d417.

I get following errors with this commit applied:

    dec 13 19:17:40 laptop libvirtd-pre-start[8951]: grep: /etc/libvirt/qemu/*.xml: No such file or directory
    dec 13 19:17:40 laptop libvirtd-pre-start[8951]: sed: /etc/libvirt/qemu/*.xml ni mogoče prebrati: No such file or directory
    dec 13 21:04:33 laptop libvirtd-pre-start[10397]: grep: /etc/libvirt/qemu/*.xml: No such file or directory
    dec 13 21:04:33 laptop libvirtd-pre-start[10397]: sed: /etc/libvirt/qemu/*.xml ni mogoče prebrati: No such file or directory