Change group_overview feature specs to use translated strings

What does this MR do?

Contributes to #214654

This is the follow up MR for !29278 (merged) which changes specs in ee/spec/features/groups/group_overview_spec.rb to use translated strings instead of hard coded ones. For more information you can check the comments.

/closes #214660 (closed)

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content