Revert "Make the first call go through pickle as well."

This reverts commit 4f4ae1a.

Author: xi-db

python/pyspark/sql/connect/dataframe.py

@@ -1848,15 +1848,13 @@ def _schema(self) -> StructType:
 
     @property
     def schema(self) -> StructType:
-        # self._schema call will cache the schema and serialize it if it is not cached yet.
-        _schema = self._schema
         if self._cached_schema_serialized is not None:
             try:
                 return CPickleSerializer().loads(self._cached_schema_serialized)
             except Exception as e:
                 logger.warn(f"DataFrame schema pickle loads failed with exception: {e}.")
         # In case of pickle ser/de failure, fallback to deepcopy approach.
-        return copy.deepcopy(_schema)
+        return copy.deepcopy(self._schema)
 
     @functools.cache
     def isLocal(self) -> bool:

python/pyspark/sql/tests/connect/test_connect_dataframe_property.py

@@ -74,11 +74,9 @@ def test_cached_property_is_copied(self):
 
         cdf = self.connect.createDataFrame(data, schema)
         cdf_schema = cdf.schema
-        assert len(cdf._cached_schema_serialized) > 0
         assert cdf_schema.jsonValue() == cdf._cached_schema.jsonValue()
         assert len(cdf_schema.fields) == 4
         cdf_schema.fields.pop(0)
-        assert cdf.schema.jsonValue() == cdf._cached_schema.jsonValue()
         assert len(cdf.schema.fields) == 4
 
     def test_cached_schema_to(self):