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/dependency.py b/api/controller/dependency.py
index ae0aaf1..47d9660 100644
--- a/api/controller/dependency.py
+++ b/api/controller/dependency.py
@@ -17,7 +17,7 @@
 from chromite.api.controller import controller_util
 from chromite.api.gen.chromite.api import depgraph_pb2
 # TODO(crbug/1081828): stop using build_target and drop it from the proto.
-from chromite.lib import cros_build_lib
+from chromite.lib import build_target_lib
 from chromite.lib.parser import package_info
 from chromite.service import dependency
 
@@ -76,7 +76,7 @@
   else:
     # TODO(crbug/1081828): stop using build_target and drop it from the proto.
     board = input_proto.build_target.name
-    sysroot_path = cros_build_lib.GetSysroot(board or None)
+    sysroot_path = build_target_lib.get_default_sysroot_path(board or None)
 
   packages = tuple(
       controller_util.PackageInfoToCPV(x) for x in input_proto.packages)