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/tricium_clang_tidy.py b/scripts/tricium_clang_tidy.py
index 93fd68b..dc8cc54 100644
--- a/scripts/tricium_clang_tidy.py
+++ b/scripts/tricium_clang_tidy.py
@@ -41,8 +41,6 @@
                     Union)
 
 import yaml  # pylint: disable=import-error
-
-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
@@ -446,8 +444,7 @@
   packages = [x.package for x in ebuild_list]
   logging.info('Setting up to lint %r', packages)
 
-  workon = workon_helper.WorkonHelper(
-      build_target_lib.get_default_sysroot_path(board))
+  workon = workon_helper.WorkonHelper(cros_build_lib.GetSysroot(board))
   workon.StopWorkingOnPackages(packages=[], use_all=True)
   workon.StartWorkingOnPackages(packages)
 
@@ -478,8 +475,7 @@
   # Since we rely on build actions _actually_ running, we can't live with a
   # cache.
   osutils.RmDir(
-      Path(build_target_lib.get_default_sysroot_path(
-          board)) / 'var' / 'cache' / 'portage',
+      Path(cros_build_lib.GetSysroot(board)) / 'var' / 'cache' / 'portage',
       ignore_missing=True,
       sudo=True,
   )