Improve testing around the GDK report command

Overview

Currently, the related unit tests for the GDK report command heavily rely on mocking. Therefore, the current tests are weak and only represent a fraction of the actual behaviour.
This issue is about refactoring the mentioned tests and increasing testing security.

Impacted categories

The following categories relate to this issue:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Steps to replicate

1. Run bundle exec rspec spec/lib/gdk/command/report_spec.rb.