Fix removal of policies which have reached limits

What does this MR do and why?

Fixes two bugs of the same kind introduced by !146760 (merged) and !186095 (merged): Both MRs added a policy validation that enforces an action/rule limit, but these validations also apply when attempting to remove a policy that exceeds these limits, effectively blocking their removal.

References

• !146760 (merged)
• !186095 (merged)

How to set up and validate locally

For example to test the removal of a policy that exceeds the upcoming action limit of 10, first ensure the feature flag is disabled:

echo "Feature.disable(:scan_execution_policy_action_limit)" | rails c

Create a new project, navigate to Secure > Policies and create the following Scan execution policy:

scan_execution_policy:
  - name: Secret detection
    enabled: true
    rules:
      - type: pipeline
        branches:
          - '*'
    actions:
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection
      - scan: secret_detection

Enable the feature flag:

echo "Feature.enable(:scan_execution_policy_action_limit)" | rails c

• Verify that you cannot save the policy in its current form, because Policy exceeds the maximum of 10 actions.
• Verify that you can delete the policy

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.