chore: remove bazel

Created by: jhchabran

Bazel was initially added here as a convenience for using this from the monorepo, but ultimately, we don't use it at all. And as this repo is merely a simple Go codebase with nothing fancy or slow tests, it's not that a good case for Bazel. Finally, we're not using it in CI either, it's GHA, so it has a tendency to drift.

Fixes https://github.com/sourcegraph/devx-support/issues/228

Test plan

CI