Remove au_nton path from update URLs

Previously devserver would rename all update payloads (full and delta)
to update.gz. So we needed a different path to differentiate the delta
payload's location. But now, devservers don't do that anymore, so we can
drop this additional path and just identify in the update URL which
type we want using the full_payload search query.

BUG=chromium:1149703
TEST=test_that --args="job_repo_url=http://100.115.168.195:8082/static/reef-release/R88-13591.0.0/autotest/packages" chromeos6-row3-rack10-host5.cros autoupdate_ForcedOOBEUpdate.delta

Change-Id: If4f36661344b13618c1121e93621d486dc5d4339
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2570556
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Commit-Queue: David Haddock <dhaddock@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Auto-Submit: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: David Haddock <dhaddock@chromium.org>
(cherry picked from commit d5237db55ab093e4a9e4afab9df56f407280d015)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2598260
Tested-by: Kyle Shimabukuro <kyleshima@chromium.org>
Commit-Queue: Kyle Shimabukuro <kyleshima@chromium.org>
diff --git a/server/cros/update_engine/update_engine_test.py b/server/cros/update_engine/update_engine_test.py
index 04de5c8..c2a6913 100644
--- a/server/cros/update_engine/update_engine_test.py
+++ b/server/cros/update_engine/update_engine_test.py
@@ -757,11 +757,6 @@
         # Use the same lab devserver to also handle the update.
         url = self._autotest_devserver.get_update_url(build)
 
-        # Delta payloads get staged into the 'au_nton' directory of the
-        # build itself. So we need to append this at the end of the update
-        # URL to get the delta payload.
-        if not full_payload:
-            url += '/au_nton'
         logging.info('Update URL: %s', url)
         return url