[ios] Fixes testExportFlow egtest on iOS 13.1

There was a change on iOS13.1 where the were multiple buttons matching
the Close label. This CL adds an extra matcher to differentiate between
the two.

Bug: 1012341
Change-Id: Ia4d20bcf0797d8ba32551ce5da2944aad0d06882
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1850780Reviewed-by: Chris Lu <thegreenfrog@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704400}

ios/chrome/browser/ui/settings/password/passwords_settings_egtest.mm

@@ -1556,8 +1556,10 @@ PasswordForm CreateSampleFormWithIndex(int index) {
     [[EarlGrey
         selectElementWithMatcher:grey_allOf(
                                      ButtonWithAccessibilityLabel(dismissLabel),
-                                     grey_interactable(), nullptr)]
-        performAction:grey_tap()];
+                                     grey_interactable(),
+                                     grey_not(grey_accessibilityTrait(
+                                         UIAccessibilityTraitNotEnabled)),
+                                     nullptr)] performAction:grey_tap()];
   }
 
   // Wait until the activity view is dismissed.