Geo: Increase retry backoff cap for blobs missing on primary

What does this MR do and why?

Describe in detail what your merge request does and why.

Increase the exponential backoff cap of failure retries from 1 hour to 4 hours when SSF records a sync failure due to a blob being missing on the Geo primary site.

This change is effectively behind the existing feature flag #348590 (closed) since there is no behavior change if the FF is off.

Related to #348745 (closed)

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