[ios] Disables OpenInManagerTest.testOpenIn on tablet.

The test does not currently work when the share menu displays in a
popover.

BUG=983135

Change-Id: I6d9e106792b4bb383b257fd6b315e62a0fdddc23
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1698122Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676427}

ios/chrome/browser/ui/open_in/open_in_controller_egtest.mm

@@ -48,6 +48,12 @@ id<GREYMatcher> ShareMenuDismissButton() {
 // Tests that open in button appears when opening a PDF, and that tapping on it
 // will open the activity view.
 - (void)testOpenIn {
+  // TODO(crbug.com/983135): The share menu displays in a popover on iPad, which
+  // causes this test to fail.
+  if ([ChromeEarlGrey isIPadIdiom]) {
+    EARL_GREY_TEST_DISABLED(@"Disabled on iPad");
+  }
+
   // TODO(crbug.com/982845): A bug is causing the "Open in" toolbar to disappear
   // after any VC is presented fullscreen over the BVC.  The iOS 13 share menu
   // is presented fullscreen, but only when compiling with the iOS 12 SDK.