Shorten path for XDG_CONFIG_HOME and clean dir

In Linux socket paths are limited to 108 char length.
/var/tmp/vm/$UID/.config will be too long in some cases.
So we use /var/tmp/vm/$UID

/var/tmp/vm must be
- cleaned on startup
- created with sticky-bit (used by different users)

roles/lmn_vm/files/vm-run

@@ -295,7 +295,7 @@ if [[ "${PERSISTENT}" == 1 ]] && [[ ! -f "${VM_DIR_PERSISTENT}/${VM_NAME}.qcow2"
 fi
 
 # because virsh has problems with long pathnames, using diffent configdir
-export XDG_CONFIG_HOME="/var/tmp/vm/${UID}/.config"
+export XDG_CONFIG_HOME="/var/tmp/vm/${UID}"
 
 if  ! virsh --connect="${QEMU}" list | grep "${VM_NAME}-clone"; then
     echo "VM not yet running."