Switch some bundles to use Axios

What does this MR do?

EE MR, https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3808

• Switch from vue-resource to Axios
  • issue_show
  • vue_merge_request_widget
  • blob/notebook
  • boards
• Switching to Axios means we fix Ajax ~bug's with IE (more than what is actually reported)

Are there points in the code the reviewer needs to double check?

This can be reviewed by commit. Each commit is a clean mergeable chunk.

Why was this MR needed?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

See #34534 (moved)

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/41043