[#24789] Spot fix fullvalue wrapping for SDF.

[lostluck]

Discovered there's an inconsistency with how FullValue wrappings occur between SDF phases and DataSource decoding. Undiscovered due to fusion hiding the inconsistency.

Discovered while adding SDF handling to the replacement runner tracked in #24789.

Ideally, there would be no such distinction, but would entail a major consistency cleanup in the execution layer. For now, we wrap if needed, but cleaning up the inconsistency would improve SDK throughput.

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[lostluck]

R:@damccorm since he's around this week.

[damccorm]

LGTM

[damccorm]

@lostluck FYI, somehow this got merged back into your own branch, not master 😕

[damccorm]

[lostluck]

Dang it. I think I have a bad rebase in there. Thanks!