Simplified build of 220.video-processing

This benchmark relies on a static build of ffmpeg, which we source from an external website. Instead of pulling the ffmpeg binary at every single build, which adds a lot of pressure on that website in CI builds and can lead to errors when pulling data (e.g., rate limits), we could put a pinned and reproducible variant of ffmpeg in our benchmarks-data instead.

We should a new resources category in benchmarks-data, and change init.sh script to copy that binary during initial build.