S3 Blobstore expiration is at Bucket level - ignores path prefix

When creating an S3 Blobstore, the expiration days can be set.

This is tied to a lifecycle policy on the S3 bucket.

When multiple S3 Blobstores are created in the same bucket - using different path prefixes - they each allow a separate setting for expiration days, however, they simply overwrite the common lifecycle policy.

Either:

1) It should be clear from the UI that they share a single lifecycle policy, and cannot be separately set.

or

2) The lifecycle policy should be maintained with appropriate filters when path prefixes are in place.

Steps to reproduce:

• Create an S3 Blobstore with path prefix of test1 and expiration days set to 10
• Run aws s3api get-bucket-lifecycle-configuration --bucket <bucketName>
• Create a second S3 Blobstore in the same bucket with path prefix of test2 and expiration days set to 20
• Run aws s3api get-bucket-lifecycle-configuration --bucket <bucketName>
• Note that the single expiration rule now has changed to 20 days.