[Storage] Move logic to create the bucket name inside the backend class

[JosepSampe]

Part of #1293, #1295

• [Storage] Move logic to create the bucket name inside the backend class

This previous change is required to allow:

• [AWS Lambda] Eliminate the need for access and secret keys in the configuration
• [AWS Batch] Eliminate the need for access and secret keys in the configuration
• [AWS S3] Eliminate the need for access and secret keys in the configuration

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