chore(python): remove false "eager=True" from date_range tests

[MarcoGorelli]

In date_range, there is

polars/py-polars/polars/functions/range.py

Lines 359 to 369 in 5c39152

	if (
	not eager
	or isinstance(start, (str, pl.Expr))
	or isinstance(end, (str, pl.Expr))
	):
	start = parse_as_expression(start)
	end = parse_as_expression(end)
	expr = wrap_expr(plr.date_range_lazy(start, end, interval, closed, time_zone))
	if name is not None:
	expr = expr.alias(name)
	return expr

So in effect, currently, if start or end are expressions, then an expression will be returned, and eager=True takes no effect (as is technically a lie?)

Noticed this while working on #9019, this'll help reduce the diff