[services] Backup - remove files for S3 operations
Summary:
The idea is that the backup service will not handle S3 directly - only via the blob service. Therefore we can remove all S3-related components from it.
Test Plan: -
Reviewers: palys-swm, geekbrother, varun, ashoat
Reviewed By: palys-swm, ashoat
Subscribers: benschac, ashoat, palys-swm, Adrian, atul
Differential Revision: https://phabricator.ashoat.com/D3078