Benchmarks generate_data.stock.realistic_4d_w_everything laziness not working

[trexfeathers]

🐛 Bug Report

Reported here: #5926 (comment)

How To Reproduce

Steps to reproduce the behaviour:

1. Call the function: my_cube = realistic_4d_w_everything(lazy=False)
2. Check laziness: print(my_cube.has_lazy_data())

Expected behaviour

Step 2 should print False, but currently prints True.

Environment

• OS & Version: [e.g., Ubuntu 20.04 LTS]
• Iris Version: [e.g., From the command line run python -c "import iris; print(iris.__version__)"]

Observed during GHA CI, and locally by @bouweandela

Additional context

iris/benchmarks/benchmarks/generate_data/stock.py

Lines 155 to 183 in 13017e3

	def realistic_4d_w_everything(w_mesh=False, lazy=False) -> iris.cube.Cube:
	"""Run :func:`iris.tests.stock.realistic_4d_w_everything` in ``DATA_GEN_PYTHON``.
	Parameters
	----------
	w_mesh : bool
	See :func:`iris.tests.stock.realistic_4d_w_everything` for details.
	lazy : bool
	If True, the Cube will be returned with all arrays as they would
	normally be loaded from file (i.e. most will still be lazy Dask
	arrays). If False, all arrays will be realised NumPy arrays.
	"""
	def _external(w_mesh_: str, save_path_: str):
	import iris
	from iris.tests.stock import realistic_4d_w_everything
	cube = realistic_4d_w_everything(w_mesh=bool(w_mesh_))
	iris.save(cube, save_path_)
	save_path = (BENCHMARK_DATA / f"realistic_4d_w_everything_{w_mesh}").with_suffix(
	".nc"
	)
	if not REUSE_DATA or not save_path.is_file():
	_ = run_function_elsewhere(_external, w_mesh_=w_mesh, save_path_=str(save_path))
	context = nullcontext() if lazy else load_realised()
	with context:
	return iris.load_cube(save_path, "air_potential_temperature")