Limit airborne to API specs only

What does this MR do?

Use airborne in API specs only. Use rest-client directly elsewhere. With the changes in this MR, we have a clarity if the get, post etc. methods used in the tests come from airborne or QA::Support::Api.

The problem:

We were requiring airborne in qa/qa/runtime/api/client.rb file to expose the REST methods it provides. This is not the best approach for the following reasons:

1. airborne is a library for testing the APIs. We should not be relying on the REST methods it provides for interacting with the APIs when not testing the APIs. We should use rest-client (via QA::Support::Api ) instead (airborne also uses rest-client underneath).
2. Requiring airborne in this file was hiding the REST method exposed by QA::Support::Api in some tests. This was discovered while making some changes to QA::Support::Api#post in another MR.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing