Fix displaying events of removed events and events without commit messages

What does this MR do?

This fixes the problems listed in:

• https://gitlab.com/gitlab-org/gitlab-ce/issues/36722
• https://gitlab.com/gitlab-org/gitlab-ce/issues/36685

When we display events of removed branches/tags we no longer show the commit details (commit ID + message), instead we display the events inline:

Does this MR meet the acceptance criteria?

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