[services] Backup - Update proto file for pull backup
Summary:
Depends on D3626
We don't need a stream for the request for pulling the backup. Also, removed unnecessary oneof. In PullBackupRequest added backup id.
Test Plan: The same as in D3535
Reviewers: geekbrother, palys-swm, ashoat
Reviewed By: palys-swm, ashoat
Subscribers: ashoat, palys-swm, Adrian, atul, benschac, yayabosh
Differential Revision: https://phabricator.ashoat.com/D3627