Fix AccessibilityTests hang on previews expecting expired transient state

The Observation migration (2d486ece3) ported the preview fulfillment loop
from Combine publishers to async sequences but didn't carry over the
publisher path's 1s timeout. Without it, a preview whose expected state never
arrives loops forever.

ElementX/Sources/AccessibilityTests/AccessibilityTestsAppCoordinator.swift

@@ -149,8 +149,14 @@ struct PreviewsWrapperView: View {
                 .makeAsyncIterator()
             while let value = await iterator.next(isolation: #isolation), value == false { }
         case .sequence(let sequence):
-            var iterator = sequence.makeAsyncIterator()
-            while let value = await iterator.next(isolation: #isolation), value == false { }
+            // Mirror the publisher timeout above so a preview expecting a state that never
+            // arrives (e.g. a transient one that already expired) doesn't hang the suite.
+            let task = Task {
+                var iterator = sequence.makeAsyncIterator()
+                while let value = await iterator.next(isolation: #isolation), value == false { }
+            }
+            DispatchQueue.main.asyncAfter(deadline: .now() + 1) { task.cancel() }
+            await task.value
         case .none:
             break
         }