[moblab] Turn on result file tar and compression

Partners have limited upload speeds, turn on the gs_offloader
option that tars and zips directories with more than 500 files.

This change affects moblab only.

BUG=chromium:715790
TEST=manual testing on a moblab

Change-Id: I0417bdb0606f9a7e1bdb57105041c30807ff2469
Reviewed-on: https://chromium-review.googlesource.com/488167
Commit-Ready: Keith Haddow <haddowk@chromium.org>
Tested-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: Jinsong Mu <jinsong@google.com>
Reviewed-by: Keith Haddow <haddowk@chromium.org>
diff --git a/moblab_config.ini b/moblab_config.ini
index 07f2ade..6f3a4fd 100644
--- a/moblab_config.ini
+++ b/moblab_config.ini
@@ -35,3 +35,5 @@
 # All moblab DUT's are in dev mode, so skip the repair check.
 dev_mode_allowed: True
 
+# Reduce upload bandwidth for partner by switching on tar and compress results.
+gs_offloader_limit_file_count: True