[prism] Catch panics in primary execution goroutines.

[lostluck]

In going over the threading model for Prism, two goroutines stood out as not handling recoverable panics.

The handling in each is to ultimately fail the job in question, with the goal of keeping the prism server instance up, and cleaning up the job's resources.

Related #29650, and #28187

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[lostluck]

R: @damondouglas

This is a quick one. The failures are due to the Java 11 migration. We're building 8, but depending on 11.

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