Don't pass registered_udf_name as argument in batch mode (#434)

This fixes an issue where with registered task graphs we would pass the
registered udf name as the first argument instead of ignoring it.

src/tiledb/cloud/dag/dag.py

@@ -1522,8 +1522,12 @@ def _build_batch_taskgraph(self):
             i = 0
             for arg in node.args:
                 i += 1
+                # Skip if first arg is function
                 if i == 1 and callable(arg):
                     continue
+                # Skip if first arg is registered udf name
+                if i == 1 and type(arg) == str and "registered_udf_name" in kwargs:
+                    continue
                 if isinstance(arg, Node):
                     if node._expand_node_output:
                         args.append(