refactor: Move unserialization of artifacts outside the loop in spark_materialization_engine

Author: Bhargav Dodla

sdk/python/feast/infra/materialization/contrib/spark/spark_materialization_engine.py

@@ -235,6 +235,13 @@ def _map_by_partition(
 ):
     feature_view, online_store, repo_config = spark_serialized_artifacts.unserialize()
     """Load pandas df to online store"""
+
+    # unserialize artifacts
+    (
+        feature_view,
+        online_store,
+        repo_config,
+    ) = spark_serialized_artifacts.unserialize()
     for pdf in iterator:
         pdf_row_count = pdf.shape[0]
         start_time = time.time()