Ideas for speeding up test execution

- [x] Make sure all previous builds are cancelled when new builds on the same PR are triggered
- [x] audit all pre & post-install scripts
- [x] perhaps copy over node modules between packages, since they're identical, vs. reinstalling? or installing centrally?
- [x] Submitting a failing check immediately if a test fails early
- [ ] Remove `compileProtos` step by instead doing it when running the generator and copying over to googleapis-gen
- [x] Perhaps - don't run linting on templated files, as these will always get overwritten by the post-processor