core: remove dead code

[schmichael]

hasAlloc was only ever false, so it could never return JobStatusDead

Or perhaps #25081 should have re-added hasAlloc = true like it was in #24974? Checking with @mismithhisler

Description

Testing & Reproduction steps

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[tgross]

The second sentence here appears to be accurate, but the first sentence no longer is because we're not considering terminal vs GC'd allocs. We should probably update this language and the language in the comment at the bottom of the function.