[services] Tunnelbroker - Fix uninformative test names

Summary: Some of the tests have uninformative names. We are going to follow the informative test names approach and this diff fixes some tests names that were approved before the discussion about the names.

Test Plan: Run yarn test-tunnelbroker-service and successfully built and test the service.

Reviewers: karol-bisztyga, varun, ashoat

Reviewed By: karol-bisztyga, ashoat

Subscribers: ashoat, palys-swm, Adrian, atul, karol-bisztyga, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3924