[services] Use ensure! macro where possible

Summary:
Resolves ENG-1840. It was suggested to use anyhow::ensure! macro instead of bail! where possible.
There were only few places, where such replacement was possible, as most of the code use bail! with if let which cannot be easily transformed into ensure!.

Test Plan:

• Backup service container builds
• Service integration tests pass

Reviewers: marcin, jon

Reviewed By: jon

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5340