Cleanup User-Driven Shield Jobs and Targets

[ampersand8]

Problem

Open Service Broker creates a target and a job on shield when user requests a backup (see here). Those will never be deleted, even when the service instance is being cleaned up.

Requirements

• Cleanup shield jobs of deleted service instances
• Cleanup shield targets of deleted service instances
• Do not fail service deprovisioning because of failing shield deregistration

Proposal

This functionality could be added with the existing notifyServiceInstanceDeletion, either at deprovisioning (should be async in that case) or with the service instance cleanup job.