Fix tooltips on group "Shared projects" view

Description

@pslaughter commented

issue (non-blocking): Just noticed an unrelated issue that the tooltips for the shared projects seem to say "Group" when they should say "Project" 🤔

I'll create an issue for this 👀

Implementation guide

1. Add this.isGroup check to app/assets/javascripts/groups/components/group_item.vue#L104. Use app/assets/javascripts/visibility_level/constants.js#L36 if this.isGroup is false.