Previously, we were emptying root.pendingInteractionMap and permanently losing those interactions when applying an unrelated update to a tree that has no scheduled work that is waiting on promise resolution. (That is, one that is showing a fallback and waiting for the suspended content to resolve.)
The logic I'm leaving untouched with `nextRenderIncludesTimedOutPlaceholder` is *not* correct -- what we want is instead to know if *any* placeholder anywhere in the tree is showing its fallback -- but we don't currently have a better replacement, and this should unblock tracing with suspense again.
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