[services] Tunnelbroker - Fix dynamoDB fields names from Id to ID

Summary:
Refactor dynamoDB table tames in database entities (FIELD_*) from *Id to *ID in Tunnelbroker to make the codebase consistent.

Linear task: ENG-711

Test Plan: Run yarn test-tunnelbroker-service all tests are run and succeed.

Reviewers: karol-bisztyga, varun, ashoat

Reviewed By: ashoat

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

Differential Revision: https://phabricator.ashoat.com/D3899