Improve testing of the GDK predictive command

Overview

During the implementation of the gdk predictive command, the added RSpec tests use too much mocking. That reduces the value they add.
Revisit the created RSpec tests and reduce the amount of mocking.

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

bundle exec rspec spec/lib/gdk/command/predictive_spec.rb spec/lib/gdk/predictive/base_spec.rb spec/lib/gdk/predictive/rspec_spec.rb spec/lib/gdk/predictive/jest_spec.rb

Proposal

Reduce the mocking.