refactor external asset pipeline handling

What does this MR do?

Remove rollup/pipeline.sh from being called by every job:

• Change the external_pipeline in main config to only be called outside of CI (only for local builds and development mode).
• Change yarn command which invokes rollup.js from bundle to build to avoid confusion with Ruby gems bundle command.
• Create new dedicated asset-build-and-deploy job which just directly calls rollup.js and deploys tmp/frontend/javascripts/ to public/javascripts and publish it as an artifact.
• Remember to add as a dependency to review-prep-bucket and deploy-cleanup-old-deleted-files jobs.

Related issues

Relates #8302 (closed)