Refactor StorageTypeFileIO discriminator to support S3 Tables without opt-out

[aritragster]

Is your feature request related to a problem? Please describe.

Description

PR #4052 adds S3 Tables support with validateAllowedStorageType=false as a workaround because both S3 and S3 Tables resolve to S3FileIO, making
StorageTypeFileIO unable to discriminate between them based on FileIO class alone.

Problem

The current discriminator assumes a 1:1 mapping between storage type and FileIO implementation. S3 Tables breaks this assumption since it uses the same
S3FileIO as standard S3 but requires different credential vending logic (different IAM actions, different ARN format).

Describe the solution you'd like

Proposed Fix

Refactor the discriminator to use a richer signal than FileIO class — e.g., the signingName from the catalog config, the ARN prefix
(arn:aws:s3tables), or a dedicated storage type field on the catalog entity.

Context

Follow-up from review feedback on #4052 by @flyingImer. The current opt-out is functional but circumvents the validation contract rather than fixing
it.

Describe alternatives you've considered

No response

Additional context

No response