boxster: update DeviceStability file path

BUG=b/195589460
TEST=./run_py_unittests.sh; ./run_go_unittests.sh; manual testing

Change-Id: I2bd7a762258b67bdcb59cc0c20d16c6a1723672a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/config/+/3145549
Reviewed-by: Sean McAllister <smcallis@google.com>
Commit-Queue: Justin Suen <justinsuen@google.com>
diff --git a/payload_utils/config_to_datastore.py b/payload_utils/config_to_datastore.py
index 2d52b9f..ded13de 100755
--- a/payload_utils/config_to_datastore.py
+++ b/payload_utils/config_to_datastore.py
@@ -214,5 +214,5 @@
       os.path.realpath(
           os.path.join(
               script_dir,
-              "/../../../infra/config/testingconfig/generated/device_stability.cfg"
+              "../../../infra/config/testingconfig/generated/device_stability.cfg"
           )), ufs_ds_client)