[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