[services] Backup - Tests - Pull Backup - Improve logging

Summary: Making logs clearer in the pull backup test utility

Test Plan:

cd services
yarn run-integration-tests backup

Reviewers: jon, tomek, varun, max

Reviewed By: jon, tomek

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5002