tests: qemuhotplug: Don't free the monitor object as part of @vm
tests: qemuhotplug: Don't free the monitor object as part of @vm

The test monitor should be freed separately so we need to remove the
pointer from the @vm object. This fixes a race condition crash in the
test introduced in commit a245abce43.

taget/libvirt,taget/libvirt,olafhering/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,crobinso/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,crobinso/libvirt,zippy2/libvirt,nertpinx/libvirt,taget/libvirt,andreabolognani/libvirt,nertpinx/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,datto/libvirt,datto/libvirt,VenkatDatta/libvirt,libvirt/libvirt,olafhering/libvirt,crobinso/libvirt,jfehlig/libvirt,andreabolognani/libvirt,nertpinx/libvirt,crobinso/libvirt,jardasgit/libvirt,datto/libvirt,jfehlig/libvirt,jardasgit/libvirt,andreabolognani/libvirt,zippy2/libvirt,libvirt/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,eskultety/libvirt,olafhering/libvirt,eskultety/libvirt,VenkatDatta/libvirt,taget/libvirt,eskultety/libvirt,taget/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jardasgit/libvirt,eskultety/libvirt,olafhering/libvirt,eskultety/libvirt,jardasgit/libvirt,datto/libvirt,VenkatDatta/libvirt,zippy2/libvirt,libvirt/libvirt,jfehlig/libvirt,datto/libvirt,zippy2/libvirt