Revert "Use minimal Bazel for downstream projects. (#428)" (#429) This reverts commit d24015f91b32217ddb2cb45ecded7c498e0e3c4f. We decided it's better to actually change what //src:bazel refers to and add a //src:bazel-dev instead.
See https://github.com/bazelbuild/continuous-integration/blob/master/buildkite/README.md