qemu: Use short domain name in qemuDomainGetPreservedMountPath
qemu: Use short domain name in qemuDomainGetPreservedMountPath

Otherwise longer domain names might generate paths that are too long
to be created.  This follows what other parts of the code do as well.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1453194

Signed-off-by: Martin Kletzander <e82f23e74d43760279ebcc505dac4ae70d5627d0@redhat.com>

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