Revert "[iOS][ContextMenus] Fixes ContentSuggestions preview"

This reverts commit 6c47dde7.

Reason for revert: The fix creates a pop-in animation (when closing
the menu) issue which is worse than the initial bug.

Original change's description:
> [iOS][ContextMenus] Fixes ContentSuggestions preview
>
> This CL fixes the dismissal animation of most visited tiles.
> Most Visited tile appears blank for a moment switching from incognito to
> normal tab after opening the link in a new incognito tab from context
> menu because there was no preview configured.
> To fix this, the view of the ContentSuggestionsViewController is used as
> a preview.
>
> see: https://drive.google.com/drive/folders/1EZFa-TvlJRsqVp6mwMBz0H7e6EZL0c7e?usp=sharing
>
> Bug: 1117487
> Change-Id: I1d80592e566c92cdd3b9846e74a4af53d697ee47
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2526086
> Reviewed-by: Gauthier Ambard <gambard@chromium.org>
> Commit-Queue: Ewann Pellé <ewannpv@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#825349}

TBR=gambard@chromium.org,ewannpv@chromium.org

Change-Id: I579c1637e66efa707144a716fd3810cd2de62d32
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1117487
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2526925Reviewed-by: Sebastien Lalancette <seblalancette@chromium.org>
Commit-Queue: Sebastien Lalancette <seblalancette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825356}

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

@@ -495,14 +495,6 @@ NSString* const kContentSuggestionsMostVisitedAccessibilityIdentifierPrefix =
   return cell;
 }
 
-- (UITargetedPreview*)collectionView:(UICollectionView*)collectionView
-    previewForDismissingContextMenuWithConfiguration:
-        (UIContextMenuConfiguration*)configuration API_AVAILABLE(ios(13.0)) {
-  UITargetedPreview* preview =
-      [[UITargetedPreview alloc] initWithView:self.view];
-  return preview;
-}
-
 - (UIContextMenuConfiguration*)collectionView:(UICollectionView*)collectionView
     contextMenuConfigurationForItemAtIndexPath:(NSIndexPath*)indexPath
                                          point:(CGPoint)point