[Native] Remove tunnelbroker grpc code from native library

Summary:
Remove more references to tunnelbroker.proto

Part of https://linear.app/comm/issue/ENG-3660

Test Plan:
rebuilt iOS app, and was able to log in
test gates

Reviewers: varun, ashoat, tomek, bartek

Reviewed By: bartek

Subscribers: atul

Differential Revision: https://phab.comm.dev/D7436