[lib] Skip Tunnelbroker QR auth message if decryption fails

Summary:
Continuation ENG-8131.
We should skip Tunnelbroker messages that cannot be decrypted.

Depends on D12104

Test Plan: Repeated repro steps from Linear

Reviewers: ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12117