Auto-Stop Workers

Currently, we start `{n}` Workers and fully let them finish.
Then we ignore all first 500frames of its output and continue with the rest of the data.

However this takes a lot of time. Idealy the Script would only run a singular worker for a few hundred frames (after 500) and then stop.
This would speed up the tests significantly, as we would not have to wait for workers to finish transcoding the ENTIRE file.

Start by tracing where workers are started and where the first 500 frames are discarded. Determine how a worker can process only a few hundred frames after that point and what existing benchmark or execution checks cover this path. Done means the benchmark stops the limited worker work without waiting for full-file transcoding while preserving the intended measurements.

Written by the indexing model from the issue text.