Use precompiled GitLab Workhorse binaries in gitlab/tmp/tests

Overview

Similar to #2444 (closed), GitLab Workhorse compiles during RSpec setup even when skip_compile: true is configured in GDK.

We can improve this by adding precompiled GitLab Workhorse binaries so it doesn't need to compile.

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.