zsh-completion: Do not interpret escape sequences in _filter_units_by_property

This makes all functions that rely on _filter_units_by_property() (like
_systemctl_{stop,kill,try_restart}) work with unit names that contain backslash
escaped sequences (like automount units with spaces that are escaped to
"\x20").

shell-completion/zsh/_systemctl.in

@@ -137,7 +137,7 @@ _filter_units_by_property() {
     unit=${units[i]}
     prop=${(f)"$(_call_program units "$service show --no-pager --property="$property" ${unit} 2>/dev/null")"}
     if [[ "${prop}" = "$property=$value" ]]; then
-      echo " ${unit}"
+      echo -E - " ${unit}"
     fi
   done
 }