ci: Improve execution times of exceptionally slow tests (>10 minutes)

We should make an effort to improve execution time for any tests which exceed 10 minutes. Specifically, there are three tests which fall in this category which can be improved:

- `DocFX tests`: These iterate over all 100+ components, and could be improved by executing these tests in parallel.
- `Individual Package tests`: These also iterate over all 100 components, and can be improved by running them in parallel.
- `Breaking Change Detector`: This is a bit more complicated, as the breaking change detector is not configurable, and executes by comparing git branches. We can look into it, but one potential way to improve this is to add logic which only runs the breaking change detector in the sub-directory which the changes are made in. This could work by cloning the sub-repo, using the `split` tool to add the new changes`, and comparing them to the previous commit.