finish build_target_lib.get_default_sysroot_path migration [reland]

This allows us to drop the build_target_lib import from cros_build_lib.

The failing platform2 code that caused this to revert before has been
fixed, and cs/ doesn't show any other latent hits.

BUG=chromium:1170007
TEST=CQ passes

Change-Id: I284d99fc2570eff7c4e843140efdfe5a56acc8d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2814898
Tested-by: Mike Frysinger <vapier@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Sergey Frolov <sfrolov@google.com>
Reviewed-by: Sergey Frolov <sfrolov@google.com>
diff --git a/api/controller/test.py b/api/controller/test.py
index 4ef4f58..7368f85 100644
--- a/api/controller/test.py
+++ b/api/controller/test.py
@@ -19,6 +19,7 @@
 from chromite.api.controller import controller_util
 from chromite.api.gen.chromite.api import test_pb2
 from chromite.cbuildbot import goma_util
+from chromite.lib import build_target_lib
 from chromite.lib import constants
 from chromite.lib import cros_build_lib
 from chromite.lib import image_lib
@@ -40,7 +41,7 @@
 
   if not sysroot_path:
     if target_name:
-      sysroot_path = cros_build_lib.GetSysroot(target_name)
+      sysroot_path = build_target_lib.get_default_sysroot_path(target_name)
     else:
       cros_build_lib.Die("The sysroot path or the sysroot's build target name "
                          'must be provided.')