Fix fenced code block misalignment in events/activity

What does this MR do?

• Fix fenced code block misalignment in events/activity

Before	After

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

Some scale of impact notes:

• .event-item is only used within the events/_event partial.
• .event-note is only used within the events/event/_common(but no markdown) and events/event/_note partials.

The fenced code pre style is scoped to .event-item .event-note

Pages where events are used

• User profile, ex. /root
• Group Activity, ex. /groups/foo/activity
• Project Activity, ex. /foo/bar/activity

Does this MR meet the acceptance criteria?

• Tests
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #31263 (closed)