[tunnelbroker] Enable Auto-ACK for AMQP consumers

Summary:
Addresses ENG-9510.
Details in the comment.

Depends on D13621

Test Plan:
Ran Commtest several times and observed RabbitMQ dashboard.
Test results at the bottom of this comment.

Reviewers: kamil

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13622