ConstructSnapshot + BarrageMessageProducer: Use Static ConstructSnapshot Fast Path

[nbauernfeind]

This fixes the following query:

def static_right = emptyTable(1).update("Test = `test`")
Thread.start {
    result = emptyTable(1000).join(static_right)
}.join()

The result table is a static table built without an ExecutionContext, as should be allowed.

However, the captured update graph is the PoisonedUpdateGraph which throws in ConstructSnapshot. While ConstructSnapshot allows for a null UpdateGraph, the SnapshotControl does not "go through the motions" of an otherwise typical snapshot.

Conveniently, this fix will snapshot static tables (even those that capture a valid UpdateGraph) to work their way through ConstructSnapshot with less hassle, no locks, and no unnecessary retries.