Refresh sample10 metric JSON exports to null

artifacts/results/metric_iter31_sample10_all_metrics_verify/episode69/episode69.metrics.json

@@ -11,10 +11,10 @@
   "retrieve_cross_frame": -1,
   "ready_cross_frame": 236,
   "ordering_ok": true,
-  "dense_boundary_error_to_retrieve_frames": NaN,
+  "dense_boundary_error_to_retrieve_frames": null,
   "dense_boundary_error_frames": 89.0,
   "dense_boundary_error_fraction": 0.2807570977917981,
-  "key_boundary_error_to_retrieve_keyframes": NaN,
+  "key_boundary_error_to_retrieve_keyframes": null,
   "key_boundary_error_keyframes": 1.0,
   "auroc_vret_ypre_three": 0.988919878296146,
   "auprc_vret_ypre_three": 0.9801591486375134,
@@ -24,9 +24,9 @@
   "auprc_ppre_ypre": 1.0,
   "auroc_pext_yext": 1.0,
   "auprc_pext_yext": 1.0,
-  "auroc_phase_yretrieve": NaN,
-  "auprc_phase_yretrieve": NaN,
-  "f1_phase_yretrieve": NaN,
+  "auroc_phase_yretrieve": null,
+  "auprc_phase_yretrieve": null,
+  "f1_phase_yretrieve": null,
   "auroc_phase_yready": 0.9915254237288136,
   "auprc_phase_yready": 0.9529411764705882,
   "f1_phase_yready": 0.645418326693227,