Invalid "This group doesn't have any members yet".

**Describe the bug**
If a group only has "creator" and "admin" members, the message on the group page says "This group doesn't have any members yet".

**To Reproduce**

1. Create a group
2. Confirm the group
3. Add few admins to the group
4. Go to the group page
5. See the message at the top of the page

**Expected behavior**
I would not expect to see a message stating the group doesn't have any members when it clearly has members below the message.

**Extra data**

• Device: (any)
• Device OS: (any)
• Browser: (any)
• Decidim Version: 0.25, 0.26, etc.
• Decidim installation: (any)

**Additional context**
We often create specific groups only for admins, so this message is very confusing for them.