use an initial random design with grid size is 1

[topepo]

tune:::create_initial_set() will use dials::grid_space_filling() when an integer is passed.

We have space-filling designs for 2+ points and when grid = 1, it creates a random grid but uses a LHD and issues a warning:

Due to the small size of the grid, a Latin hypercube design will be used.

We can get a random point via grid_random() without the warning.

finetune::tune_sim_anneal() defaults to a 1-point initialization so no warning would be good.