Revert "finish build_target_lib.get_default_sysroot_path migration"

This reverts commit d8d25cdd41261fcc7dcfe1baf7a1b8a965faf183.

Reason for revert: suspected to cause crbug.com/1196818

BUG=chromium:1196818
TEST=CQ+1 and see if this resolves build issues

Original change's description:
> finish build_target_lib.get_default_sysroot_path migration
>
> This allows us to drop the build_target_lib import from cros_build_lib.
>
> BUG=chromium:1170007
> TEST=CQ passes
>
> Change-Id: Icf01d140baa482014acfca800a57db7bb1bdc934
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2810800
> Reviewed-by: Sergey Frolov <sfrolov@google.com>
> Commit-Queue: Mike Frysinger <vapier@chromium.org>
> Tested-by: Mike Frysinger <vapier@chromium.org>

Bug: chromium:1170007
Change-Id: I3bb147420bb75b9076a5725a2005e737412aeed0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2811778
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/scripts/cros_choose_profile.py b/scripts/cros_choose_profile.py
index 88461e9..af2aed6 100644
--- a/scripts/cros_choose_profile.py
+++ b/scripts/cros_choose_profile.py
@@ -13,7 +13,6 @@
 
 import six
 
-from chromite.lib import build_target_lib
 from chromite.lib import commandline
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_logging as logging
@@ -229,7 +228,7 @@
     if self._board_root:
       return self._board_root
 
-    return build_target_lib.get_default_sysroot_path(self.board_variant)
+    return os.path.join(cros_build_lib.GetSysroot(self.board_variant))
 
   @property
   @PathPrefixDecorator