[tunnelbroker] Removed unused include directives

Summary: Just a minor thing I noticed while testing some of the nix tunnelbroker diffs.

Test Plan: NA, CI?

Reviewers: jon, abosh, varun, tomek, max, karol

Reviewed By: jon, abosh, varun

Subscribers: ashoat, adrian

Differential Revision: https://phab.comm.dev/D4773