amarisoft/file_server: move serving directory The binaries would get cleaned out of /tmp and this would cause serving to fail. BUG=None TEST=deploy to amarisoft callbox, run, check logs Change-Id: I3ed0cd906f7fe64f0a1219ab6046a1c432d06310 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/7726646 Reviewed-by: Andrew Lassalle <andrewlassalle@chromium.org> Auto-Submit: Eric Caruso <ejcaruso@chromium.org> Commit-Queue: Eric Caruso <ejcaruso@chromium.org> Tested-by: Eric Caruso <ejcaruso@chromium.org>