[lib] Specify dontPrefixCreator when shimming UPDATE_RELATIONSHIP

Summary: Without this, the shimmed message appears as "You Your connection on Farcaster is on Comm." dontPrefixCreator fixes the issue for notifs, robotext, and message previews.

Test Plan: Confirm that the "You " prefix is gone in robotext and message previews

Reviewers: atul, ginsu

Reviewed By: ginsu

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D11868