[Bazel CI] Build aborted due to missing dependency on @protobuf

[sgowroji]

CI: https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/4170#019255c7-3451-4eeb-a0cf-6063d87311c6

Platform: MacOS

Logs:

 ERROR: no such package '@@[unknown repo 'protobuf' requested from @@_builtins]//bazel/private': The repository '@@[unknown repo 'protobuf' requested from @@_builtins]' could not be resolved: No repository visible as '@protobuf' from repository '@@_builtins'
(06:27:42) ERROR: /Users/buildkite/builds/bk-macos-pln3-4w7g/bazel-org-repo-root/rules_go/tests/bcr/proto/BUILD.bazel:4:14: While resolving toolchains for target //proto:foo_proto (57e6f54): com.google.devtools.build.lib.packages.BuildFileNotFoundException: no such package '@@[unknown repo 'protobuf' requested from @@_builtins]//bazel/private': The repository '@@[unknown repo 'protobuf' requested from @@_builtins]' could not be resolved: No repository visible as '@protobuf' from repository '@@_builtins'
(06:27:42) ERROR: Analysis of target '//proto:foo_proto' failed; build aborted
(06:27:42) INFO: Elapsed time: 16.086s, Critical Path: 0.05s
(06:27:42) INFO: 1 process: 1 internal.
(06:27:42) ERROR: Build did NOT complete successfully

Culprit:

Steps:

git clone https://github.com/bazelbuild/rules_go
git reset 76ada20edece912ab857e053f6aadd55189756d3  --hard
export USE_BAZEL_VERSION=166eaa09f9cd31836df898ea236e1e0633a73b12
bazel build  //... @go_default_sdk//... 

CC Greenteam @mai93

[fmeum]

@comius @Wyverald Looks like builtins lack protobuf in their repo mapping.

[fmeum]

@comius told me that this is expected and will be fixed by a follow-up Bazel commit that autoloads protobuf.