nebraska.py: Deprecate requestlog API

We don't use this API anymore. Instead we parse the update_engine logic
to get these information.

BUG=b:181064515
TEST=./nebraska_unittest.py

Change-Id: I48197b48b38e389d117bff33365f53a4b342dd5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2717444
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Kyle Shimabukuro <kyleshima@chromium.org>
Reviewed-by: David Haddock <dhaddock@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
2 files changed