xbuddy: Remove xbuddy files from platform.

Delete the following files:
android_build.py
artifact_info.py
build_artifact.py
build_artifact_unittest.py
build_util.py
common_util.py
common_util_unittest.py
devserver_constants.py
downloader.py
downloader_unittest.py
log_util.py
retry.py
xbuddy.py
xbuddy_unittest.py
shadow_xbuddy_config.ini
xbuddy_config.ini

Update the imports in the following files:
autoupdate.py
autoupdate_unittest.py
builder.py
cros_update_progress.py
devserver.py
devserver_integration_test.py
health_checker.py

Rename log_util.py to cherrypy_log_util.py

Remove files from Makefile

Fix lint errors in builder.py

Patchset 1 is the file deletion, subsequent patchsets have code changes.

BUG=chromium:1003986
TEST=unittests, cros flash, devserver_integration_test

Cq-Depend: chromium:1894475
Change-Id: I4e70d0971eda00263a69906a6c1b11a3014d947c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/1893644
Tested-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Achuith Bhandarkar <achuith@chromium.org>
diff --git a/devserver_integration_test.py b/devserver_integration_test.py
index 0cfcc98..502da78 100755
--- a/devserver_integration_test.py
+++ b/devserver_integration_test.py
@@ -34,10 +34,10 @@
 import psutil  # pylint: disable=import-error
 
 import cros_update_progress
-import devserver_constants
 
 import setup_chromite  # pylint: disable=unused-import
 from chromite.lib import cros_logging as logging
+from chromite.lib.xbuddy import devserver_constants
 
 
 # Paths are relative to this script's base directory.