Show both members of 2-member group in default profile photo

[saulmc]

No description provided.

[darickdang]

Not sure if we can do this proposal below but let me know if it does/doesn't work:

Figma link: https://www.figma.com/design/p6mt4tEDltI4mypD3TIgUk/Converse-App?node-id=1699-12755&t=y4l53xPO9CbsUcKz-1

[alexrisch]

Dev notes:
Remove excludeSelf prop from components/GroupAvatar.tsx
Update shouldExclude logic to check for members length
Move function for memoizedAndSortedGroupMembers into a util file and add tests

[alexrisch]

@lourou This may already be done in the Feature V3 Chat, if you can help verify

[lourou]

@alexrisch I checked, and it's done in the group chat creation screen, but not in the convos list or chat screen. Working in it!