[services] Backup - remove auth from implementation

Summary: We will no longer use authentication in the backup service.

Test Plan:

cd services
yarn run-backup-service

This should build

Reviewers: palys-swm

Reviewed By: palys-swm

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

Differential Revision: https://phabricator.ashoat.com/D3460