autoupdate.py: Deprecate autoupdate.py

This mechanism is not used in the lab anymore and has been replaced by
gs_cache/nebraska_wrapper.py in crrev.com/c/2258234.

BUG=chromium:1078188
TEST=./devserver_integration_test.py

Change-Id: Ifa007df983aab49c808360df6ba0b62b7031221c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2486466
Tested-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
5 files changed