[terraform] bump prod tunnelbroker to 0.18-amqp
Summary:
Bartek implemented a fix for issues with tunnelbroker amqp in https://linear.app/comm/issue/ENG-9412/ecsstagingtaskstopalarm-triggered-for-tunnelbroker.
He also pushed an image with the fix that we'll be deploying later this evening
Test Plan: Will test with some iOS simulators on current staging environment that personal dms are working proper before landing
Reviewers: ashoat, varun
Reviewed By: ashoat
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D13599