util: Improve scaling pattern download scripts & their docs

I noticed that the `wget` dependency wasn't documented, and since the `raw/main`-URLs were also all broken, I overhauled that script a bit. I think this also helps speed it up a bit (excluding the download duration): ``` # with wget $ hyperfine -i "bash ./util/surface/assets/scaling_patterns/01_download.sh" Time (mean ± σ): 2.187 s ± 0.958 s [User: 0.288 s, System: 0.112 s] Range (min … max): 1.316 s … 4.235 s 10 runs Warning: Ignoring non-zero exit code. # due to `main` # with curl $ hyperfine -i "bash ./util/surface/assets/scaling_patterns/01_download.sh" Time (mean ± σ): 182.2 ms ± 5.1 ms [User: 54.7 ms, System: 83.1 ms] Range (min … max): 177.9 ms … 197.6 ms 15 runs ```