[Feature] Cells 1.0 impact for file uploads

Multiple groups use upload functionality so this shared issue is for any discussions with impacted workflows.

See #434971 (comment 1790667915) for the initial thread on this.

This affects several groups:

• groupproject management (custom emojis, discussions)
• groupproduct planning (design management)
• groupauthentication (user avatars)
• grouptenant scale (project/group avatars)

(maybe others, add if you like)

Issues to be resolved

1. Routing #443573 (comment 1798607982). We likely will only route by session, not path in Cells 1.0
2. Sharding keys #443573 (comment 1832566708). uploads has no viable sharding keys. Is this needed in Cells 1.0 ?