[ios] Don't hide fake omnibox on real omnibox focus.

For historical reference, four years we started hiding this view "to prevent it from overlapping slightly with Most Visited after a device rotation when
the omnibox is focused." per: https://chromereviews.googleplex.com/99937015

It doesn't appear this is necessary anymore, and hiding that view is
causing some edge case bugs.

Bug: 703024
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Icb43e4a93b3e1675684267e2b8f4433a47acad17
Reviewed-on: https://chromium-review.googlesource.com/1185742Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585471}

ios/chrome/browser/ui/content_suggestions/content_suggestions_header_view_controller.mm

@@ -459,8 +459,6 @@ const UIEdgeInsets kSearchBoxStretchInsets = {3, 3, 3, 3};
        !content_suggestions::IsRegularXRegularSizeClass(self.view))) {
     [self.dispatcher onFakeboxBlur];
   }
-  self.fakeOmnibox.hidden = NO;
-
   [self.collectionSynchronizer shiftTilesDown];
 
   [self.commandHandler dismissModals];
@@ -476,7 +474,6 @@ const UIEdgeInsets kSearchBoxStretchInsets = {3, 3, 3, 3};
          !content_suggestions::IsRegularXRegularSizeClass(self.view))) {
       [self.dispatcher onFakeboxAnimationComplete];
       [self.headerView fadeOutShadow];
-      [self.fakeOmnibox setHidden:YES];
     }
   };
   [self.collectionSynchronizer shiftTilesUpWithCompletionBlock:completionBlock];