[services] Tests - Refactor integration tests

Summary:
In order to add performance tests, I had to do refactoring. We no longer just have "tests", we have to distinguish performance and integration tests which essentially do two different things but they should probably live next to each other because they use the same sets of tools and methods.

I also ran cargo fmt which resulted in some small changes.

Test Plan:

cd services
yarn run-integration-tests backup
yarn run-integration-tests blob

Reviewers: tomek, max, varun

Reviewed By: tomek

Subscribers: ashoat, tomek, adrian, atul, abosh

Differential Revision: https://phab.comm.dev/D4579