Signal WCI on query dispatch when no pollers available

[smuneebahmad]

What changed?

Update DispatchQueryTask to fire processTaskAddHooks signal when the selected queue has no recent pollers, using the version from syncMatchQueue directly rather than targetVersion from routing config (which can point to the wrong deployment for pinned queries). The hook only fires on non-forwarded queries to avoid duplicate invocations of serverless worker by WCI.

Why?

When Lambda workers are scaled to zero, QueryWorkflow requests were timing out silently with no scale-up signal reaching WCI. Unlike workflow and activity tasks — which have a persistent backlog that WCI polls — queries block synchronously in DispatchQueryTask waiting for a poller, so the existing ProcessTaskAdd hook in AddTask was never reached.

How did you test it?

• built
• run locally and tested manually
• covered by existing tests
• added new unit test(s)
• added new functional test(s)

[CLAassistant]

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