Bugfix: Fix rendering of object_name in GCSToLocalFilesystemOperator (#15487)

#14918 made coms consistency changes
where the template_fields was changed for ``GCSToLocalFilesystemOperator``.

While the change was correct since``object`` param was deprecated, the
instance attribute wasn't updated hence you see this error:

```
AttributeError: 'GCSToLocalFilesystemOperator' object has no attribute 'object_name'
```

Author: kaxil

airflow/providers/google/cloud/transfers/gcs_to_local.py

@@ -119,26 +119,26 @@ def __init__(
 
         super().__init__(**kwargs)
         self.bucket = bucket
-        self.object = object_name
+        self.object_name = object_name
         self.filename = filename  # noqa
         self.store_to_xcom_key = store_to_xcom_key  # noqa
         self.gcp_conn_id = gcp_conn_id
         self.delegate_to = delegate_to
         self.impersonation_chain = impersonation_chain
 
     def execute(self, context):
-        self.log.info('Executing download: %s, %s, %s', self.bucket, self.object, self.filename)
+        self.log.info('Executing download: %s, %s, %s', self.bucket, self.object_name, self.filename)
         hook = GCSHook(
             gcp_conn_id=self.gcp_conn_id,
             delegate_to=self.delegate_to,
             impersonation_chain=self.impersonation_chain,
         )
 
         if self.store_to_xcom_key:
-            file_bytes = hook.download(bucket_name=self.bucket, object_name=self.object)
+            file_bytes = hook.download(bucket_name=self.bucket, object_name=self.object_name)
             if sys.getsizeof(file_bytes) < MAX_XCOM_SIZE:
                 context['ti'].xcom_push(key=self.store_to_xcom_key, value=str(file_bytes))
             else:
                 raise AirflowException('The size of the downloaded file is too large to push to XCom!')
         else:
-            hook.download(bucket_name=self.bucket, object_name=self.object, filename=self.filename)
+            hook.download(bucket_name=self.bucket, object_name=self.object_name, filename=self.filename)