[lib] Prepend expected[Domain/URI] with web. to fix SIWE on prod

Summary: https://linear.app/comm/issue/ENG-3008/siwe-not-working-on-web

Test Plan: NA

Reviewers: ashoat, varun

Reviewed By: ashoat, varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D6737