Deflake testDialogInteractivity_BackButton on official testers

Bug: 1148747
Change-Id: Ie7d12ccd515f9a224ab025ed75a63bd70a9e4a95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2538261Reviewed-by: Filip Gorski <fgorski@chromium.org>
Commit-Queue: Brandon Wylie <wylieb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828432}

chrome/android/javatests/src/org/chromium/chrome/browser/omnibox/voice/AssistantVoiceSearchConsentUiTest.java

@@ -154,6 +154,6 @@ public class AssistantVoiceSearchConsentUiTest {
                                        ASSISTANT_VOICE_SEARCH_ENABLED, /* default= */ true),
                     is(false));
         });
-        Mockito.verify(mCallback).onResult(false);
+        Mockito.verify(mCallback, Mockito.timeout(1000)).onResult(false);
     }
 }
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