Drop trailing blank line from generated _generated/__init__.py

The package marker was written as the bare HEADER, which ends in a blank
line; the whitespace check strips it, so CI's post-checks git-diff gate
failed. Write the header with a single trailing newline instead.

Co-authored-by: Isaac <no-reply@databricks.com>

Author: Sankalp-Mittal

python/codegen/codegen/generated_wiring.py

@@ -66,7 +66,9 @@ def write_wiring(output: str):
     generated_path = core_path / "_generated"
     generated_path.mkdir(parents=True, exist_ok=True)
 
-    (generated_path / "__init__.py").write_text(HEADER)
+    # Package marker: just the generated-file header, with no trailing blank
+    # line (the whitespace check rejects one).
+    (generated_path / "__init__.py").write_text(HEADER.rstrip() + "\n")
     (generated_path / "_resource_types.py").write_text(
         HEADER + _resource_types_code(resources)
     )