Description of problem (please be detailed as possible and provide log snippests): With the inclusion of AWS STS support for Noobaa, there has been some technical debt leftovers. Some of them are 1.Validations for DefaultBackingStore under Noobaa Spec. 2. If TargetBucket is not supplied as part of Noobaa Spec, operator needs to create it before creating the backing store. 3. Validations to check for TargetBucket in DefaultBackingStore under Noobaa Spec. 4. CLI options to create AWS STS based default backing store. Version of all relevant components (if applicable): 4.10 Does this issue impact your ability to continue to work with the product (please explain in detail what is the user impact)? Is there any workaround available to the best of your knowledge? Rate from 1 - 5 the complexity of the scenario you performed that caused this bug (1 - very simple, 5 - very complex)? Can this issue reproducible? Can this issue reproduce from the UI? If this is a regression, please provide more details to justify this: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info: