This has a couple benefits:
- we now use a .bazelversion file rather than package.json to pin the version of bazel we want. This means even if you install bazel on your computer rather than via yarn, you'll still get a warning if your bazel version is wrong.
- you no longer end up downloading three copies of bazel due to bugs in both npm and yarn where they download all tarballs before checking the metadata to see which are usable on the local platform.
- bazelisk correctly handles the tools/bazel trick for wrapping functionality, which we want to use to instrument developer build latencies