Make grid_space_filling() work with qual params again

[hfrick]

Closes #447

The new stricter input checks to range_get() mean it only worked for quant parameters - however, we are not using the ranges anywhere, so I've removed the line.

library(dials)
#> Loading required package: scales

pset <- parameters(surv_dist())
grid_space_filling(pset, size = 10)
#> # A tibble: 6 × 1
#>   surv_dist  
#>   <chr>      
#> 1 logistic   
#> 2 weibull    
#> 3 loglogistic
#> 4 exponential
#> 5 gaussian   
#> 6 lognormal

^{Created on 2026-04-09 with reprex v2.1.1}