Show only group name by default and put full namespace in tooltip in Groups tree

What does this MR do?

Hides full namespace in Groups tree and shows only Group name by default, while showing full namespace as tooltip hover.

Why was this MR needed?

Groups with deep nesting lead to messy UI as we show full namespace in Group name by default which is not necessary.

Screenshots

Before

After

Default View	Tooltip on Hover

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• [ ] 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
• [ ] Internationalization required/considered

What are the relevant issue numbers?

Closes #40286 (closed)