[#32211] Fail job on SDK worker disconnect, instead of hanging forever.

[lostluck]

In working on OnWindowExpiry, it shows SDK side disconnects would cause the job to hang indefinitely if there were outstanding ProcessBundleRequests.

Instead, the job should fail (as SDK disconnects are not WAI behavior), and terminate execution instead.

Not testable as a closed form Go side without a more involved set up, but obvious in certain Python and Java side test failures. Clean job termination leads to better iteration than hangs do.

Part of #32211

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[lostluck]

R: @damondouglas

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[damondouglas]

LGTM. Agree that it's not so straightforward to setup this kind of test.