autotest: reduce default test timeout from 24hr to 6hr

Shards are accumulating a large number of backlogged jobs, most of which
are doomed to never run, but which still contribute a lot of shard rpc
and scheduler overhead.

Reduce the default timeout from 24hr to 6hr to reduce this backlog.

BUG=chromium:894197
TEST=None

Change-Id: I561cb1e3586c1a5156402c53b6544c2fc05f041b
Reviewed-on: https://chromium-review.googlesource.com/1274395
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Allen Li <ayatane@chromium.org>
diff --git a/global_config.ini b/global_config.ini
index aea04af..197cd30 100644
--- a/global_config.ini
+++ b/global_config.ini
@@ -4,9 +4,9 @@
 db_type: mysql
 user: chromeosqa-admin
 password: USE SHADOW PASSWORD
-job_timeout_default: 24
-job_timeout_mins_default: 1440
-job_max_runtime_mins_default: 1440
+job_timeout_default: 6
+job_timeout_mins_default: 360
+job_max_runtime_mins_default: 360
 parse_failed_repair_default: 0
 # Only set this if your server is not 'http://[SERVER] hostname/afe/'
 #base_url: http://your_autotest_server/afe/