Revert "[keyserver] Use old intermediate invite link page url"

Summary:
This reverts commit 42ef356dcf82063d94686ca0d7e0e845747aa892.

Context https://linear.app/comm/issue/ENG-4539/bring-back-the-old-url-scheme-on-invite-links-intermediate-page

Test Plan: Check if the link on intermediate invite link page opens the app.

Reviewers: kamil, inka

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8693