Replace the UI check with an api check for backup and restore tests

Problem Statement

We have UI tests for backup and restore which isn't ideal for following reasons

• They take longer to run
• They use data-qa-selector/ data-testid properties of the UI elements which the Distribution team doesn't control. Hence any changes in these properties, results into failures in our pipeline. CI: Fix RSpec use of QA selector, data-testid (!3276 - merged)
• They are also flaky at times e.g !3451 (comment 1622617719)

To address the above issues we need a solution and my thinking was to convert those tests to api checks rather than UI checks.

Intial thought

We have only one spec which runs the UI checks for backup and restore. All the tests in this spec can be converted to an api test rather than a UI test.

Rest Api resources for GitLab instance can be used to verify that the backup and restore tests are working as they should.