Add dot to separate system notes content

What does this MR do?

Adds a dot to separate system notes content from their timestamp

Screenshots (if relevant)

Issues

Merge requests

Epics

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
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

closes #45676 (closed)