`require 'bundler/setup'` does not respect bundler config

This was discovered at https://gitlab.com/gitlab-jh/gitlab/-/jobs/1556019024 where in the CI config we set bundle config set gemfile 'jh/Gemfile', however if we run bin/rake gitlab:assets:compile it does not respect the config and it's still using Gemfile.

I confirmed this locally. We probably need to patch bin/rake.

• Workaround: !69461 (merged)
• Bundler upstream patch: https://github.com/rubygems/rubygems/pull/4892
• Bundler bug: https://github.com/rubygems/rubygems/issues/3363