Python3 Migration: fix bytes vs strings issues

Some bytes vs strings issues were only showing up at run time
since data were passed using XMLRPC methods. This patch fixed
such issues.

BUG=b:169724328
TEST=Follow the steps to make and install with python 3
(cr) make PY_VERSION=python3
(cr) make remote-install "${CHAMELEON_HOST}" PY_VERSION=python3
(cr) Run bluetooth_AdapterQuickHealth.AVL.
     All tests should pass.

Change-Id: I643967e46f4503b32c76e703d77e806de71514b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/2573720
Commit-Queue: Shyh-In Hwang <josephsih@chromium.org>
Tested-by: Shyh-In Hwang <josephsih@chromium.org>
Reviewed-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
4 files changed