autotest: Remove senseless XmlRpc boilerplate

Python's XmlRpc framework will do this primitive marshalling for us, so
lets not duplicate it and make everyone's life miserable.

TEST=Tests pass.
BUG=None

Change-Id: Ia85505bfec935a80e2e1cb3a113ca8c5989ae97c
Reviewed-on: https://gerrit.chromium.org/gerrit/58966
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Reviewed-by: Tan Gao <tgao@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
5 files changed