Make register_instructions optional in RunnerSetup

What does this MR do?

• Makes register_instructions optional in RunnerSetup since Kubernetes and Docker don't have install instructions

Related #214587 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• N/A Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• N/A Database guides
• N/A Separation of EE specific content