[autotest] Disable incremental updating of TKO from server job.

This is meant for long running tests so that one can see progress from a
frontend, but we've never used this feature, and it's costing us mysql
connections, load, and now bugs.

BUG=chromium:385232
TEST=test_that ran fine

Change-Id: I689ae7c184d8bc6ea3b5f755150906e5031885a8
Reviewed-on: https://chromium-review.googlesource.com/205133
Reviewed-by: Prashanth B <beeps@chromium.org>
Tested-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Alex Miller <milleral@chromium.org>
2 files changed