[ios] Hide the navigation bar when displaying the bug report UI

Since the bug report UI uses a MDCAppBar, hide the navigation bar
when displaying it to avoid having the tile displayed twice which
breaks tests.

Bug: 1042741
Change-Id: I8c491be4d8a05ffa71f780896c74cd23c7a988c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2048912
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740233}

ios/chrome/browser/ui/settings/settings_navigation_controller.mm

@@ -178,6 +178,10 @@ NSString* const kSettingsDoneButtonId = @"kSettingsDoneButtonId";
       initWithRootViewController:controller
                          browser:browser
                         delegate:delegate];
+
+  // Fix for https://crbug.com/1042741 (hide the double header display).
+  nc.navigationBarHidden = YES;
+
   // If the controller overrides overrideUserInterfaceStyle, respect that in the
   // SettingsNavigationController.
   if (@available(iOS 13.0, *)) {