Update walk-study-psu.nrel-op.json

Change the `filter_time` to also be frequent (1 seconds instead of 30) per email:

> I think we want to be as consistent as possible between the two phone types. From reviewing the raw data, it seemed like the iPhones were capturing around a point per second during trips.

Author: shankari

configs/walk-study-psu.nrel-op.json

@@ -63,7 +63,8 @@
         "trip-labels": "ENKETO"
     },
     "tracking": {
-        "filter_distance": -1
+        "filter_distance": -1,
+        "filter_time": 1000
     },
     "display_config": {
         "use_imperial": true