[2/2][services] Tunnelbroker - Constants replacing with ConfigManager

Summary: Replacing usage of Constants to the ConfigManager from D2903.

Test Plan:
Successfully built, codebase parts successfully running using the getParameter.
Fails if no config file present or required config parameters present.
Assign default parameters if no parameter were specified in config file.

Reviewers: karol-bisztyga, palys-swm, varun, ashoat

Reviewed By: palys-swm, ashoat

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

Differential Revision: https://phabricator.ashoat.com/D3075