Implement deletion logic for CPMS

Background

When a CPMS is deleted, there will normally be Machines owned by the CPMS which have owner references. These owner references need to be removed to orphan the Machines before the Finalizer on the CPMS can then be removed.

This will need to be implemented here  and fulfil the tests described here.

Steps

• Review the tests cases and function description to understand what the expected behaviour is
• Implement the behaviour of the function based on prescribed behaviour in the tests
• Ensure linting passes (make lint) and think about the code layout, it is clean?
• Consider any additional tests that may need to be added

Stakeholders

• Cluster Infra (Joel)

Definition of Done

• Ensure that tests pass and that, when a CPMS is removed, it removes any owner references from existing Machines.

• Docs

• N/A

• Testing

• Consider any additional unit testing that may be required