[services] Backup - Apply reading user id in the reactors

Summary:
Depends on D3530

In the previous diff, I added a user id for every request where it was missing. Now, we want to read it when creating a new backup and sending a log.

Test Plan:

cd services
yarn run-backup-service

Reviewers: palys-swm, geekbrother, varun, jimpo

Reviewed By: palys-swm

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

Differential Revision: https://phabricator.ashoat.com/D3531