[terraform] Deploy Tunnelbroker 0.15 to staging
Summary: Deploying newest Tunnelbroker image, adding WNS work
Test Plan: Run terraform plan -target aws_ecs_service.tunnelbroker on staging.
Reviewers: bartek, marcin
Reviewed By: marcin
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D13054