[autotest] Allow gs_offloader to limit the number of files in a result folder

If the number of files is too big, try to compress each subfolder.

BUG=chromium:537756
TEST=unittest

Change-Id: I833c2664c27bc566d08a0354ea4f2695dec2ec36
Reviewed-on: https://chromium-review.googlesource.com/304090
Commit-Ready: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
diff --git a/global_config.ini b/global_config.ini
index a92a87b..72b6b78 100644
--- a/global_config.ini
+++ b/global_config.ini
@@ -291,6 +291,8 @@
 # The swarming instance that will be used for golo proxy
 swarming_proxy:
 
+# Limit the number of files in the result folder.
+gs_offloader_limit_file_count: False
 
 [BUG_REPORTING]
 gs_domain: https://storage.cloud.google.com/