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_install_debug_syms.py b/scripts/cros_install_debug_syms.py
index 24a42ab..f9dae90 100644
--- a/scripts/cros_install_debug_syms.py
+++ b/scripts/cros_install_debug_syms.py
@@ -26,7 +26,6 @@
 from six.moves import urllib
 
 from chromite.lib import binpkg
-from chromite.lib import build_target_lib
 from chromite.lib import cache
 from chromite.lib import commandline
 from chromite.lib import constants
@@ -386,7 +385,7 @@
 
   # sysroot must have a trailing / as the tree dictionary produced by
   # create_trees in indexed with a trailing /.
-  sysroot = build_target_lib.get_default_sysroot_path(options.board) + '/'
+  sysroot = cros_build_lib.GetSysroot(options.board) + '/'
 
   if options.list:
     ListInstallArgs(options, sysroot)