Replace checkout-tarballs by pristine-lfs checkout --auto

checkout-tarballs is no longer needed since pristine-lfs can do
this directly.

Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

package-source-builder/overlay/usr/bin/ci-buildpackage

@@ -22,7 +22,7 @@ dversion="$(dpkg-parsechangelog -S Version)"
 
 case "$dversion" in
     *-*)
-        checkout-tarball _build
+        pristine-lfs checkout -o _build --auto
         ;;
     *)
         ;;