text: Title: [Storage] `sky storage delete -a` aborted when deletion of one storage failed
  Body: <!-- Describe the bug report / feature request here -->
  
  `sky storage delete -a` aborted for all storage when deletion of one storage failed. Expected behaviour: print out error for corresponding storage while still delete all other storages.
  
  ```bash
  sky storage delete -a
  Deleting 7 storages: skypilot-workdir-txia-60a9b7bc, skypilot-workdir-txia-f8997026, skypilot-workdir-txia-cf42367e, skypilot-workdir-txia-4e6768c9, skypilot_test_compress, comp-289a68bd-c3ed-42bd-93b8-ee3735cdb835-0, comp-3525982f-f669-4c43-b2e7-f5a1e9789a2b-1. Proceed? [Y/n]: ^[[A
  Error: invalid input
  Deleting 7 storages: skypilot-workdir-txia-60a9b7bc, skypilot-workdir-txia-f8997026, skypilot-workdir-txia-cf42367e, skypilot-workdir-txia-4e6768c9, skypilot_test_compress, comp-289a68bd-c3ed-42bd-93b8-ee3735cdb835-0, comp-3525982f-f669-4c43-b2e7-f5a1e9789a2b-1. Proceed? [Y/n]: 
  botocore.exceptions.ClientError: An error occurred (403) when calling the HeadBucket operation: Forbidden
  
  The above exception was the direct cause of the following exception:
  
  sky.exceptions.StorageBucketGetError: Failed to access existing bucket 'skypilot-workdir-txia-60a9b7bc'. This is likely because it is a private bucket you do not have access to.
  To fix: 
    1. If you are trying to create a new bucket: use a different name.
    2. If you are trying to connect to an existing bucket: make sure your cloud credentials have access to it. To debug, consider running `aws s3 ls skypilot-workdir-txia-60a9b7bc`.
  ```
  
  