Dependency cleanup: Remove few deprecated test.util wrappers.

There are many backward compatible calls in test/utils/__init__.py and
should be removed now:
 utils.CheckOutput (process_utils.CheckOutput)
 utils.DrainQueue (type_utils.DrainQueue)
 utils.Enum (type_utils.Enum)
 utils.Error (type_utils.Error)
 utils.FlattenList (type_utils.FlattenList)
 utils.in_chroot (sys_utils.in_chroot)
 utils.is_process_alive (process_utils.IsProcessAlive)
 utils.kill_process_tree (process_utils.KillProcessTree)
 utils.LogAndCheckCall (process_utils.LogAndCheckCall)
 utils.LogAndCheckOutput (process_utils.LogAndCheckOutput)
 utils.ReadOneLine (file_utils.ReadOneLine)
 utils.Retry (sync_utils.Retry)
 utils.StartDaemonThread (process_utils.StartDaemonThread)
 utils.TimeoutError (type_utils.TimeoutError)
 utils.Timeout (sync_utils.Timeout)
 utils.TimeString (time_utils.TimeString)
 utils.WaitFor (sync_utils.WaitFor)

BUG=chromium:403712
TEST=make test

Change-Id: I82fbd7d3422f40b7a00e4b9dd09689c00b8514fd
Reviewed-on: https://chromium-review.googlesource.com/320458
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Wei-Han Chen <stimim@chromium.org>
diff --git a/py/tools/regcode.py b/py/tools/regcode.py
index 30df6af..40ff5d5 100755
--- a/py/tools/regcode.py
+++ b/py/tools/regcode.py
@@ -19,9 +19,9 @@
 from cros.factory.proto import reg_code_pb2
 from cros.factory.test import dut as dut_module
 from cros.factory.test import registration_codes
-from cros.factory.test import utils
 from cros.factory.test.registration_codes import RegistrationCode
 from cros.factory.tools.build_board import BuildBoard
+from cros.factory.utils import sys_utils
 
 
 @Command('decode',
@@ -112,7 +112,7 @@
 
     if not code:
       if rw_vpd is None:
-        if utils.in_chroot():
+        if sys_utils.in_chroot():
           sys.stderr.write('error: cannot read VPD from chroot; use -u/-g\n')
           sys.exit(1)