[iOS] Fix NTP fakebox constraints after rotation

This CL makes sure that the constraints of the fakebox are correctly
updated when there is only one toolbar.
In particular, those constraints were broken when rotating from portrait
to landscape.

Fixed: 1161448
Change-Id: I80dbfc524010915e381a4129208471b9e142b351
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2623013
Auto-Submit: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842941}

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

@@ -340,6 +340,10 @@ CGFloat ToolbarHeight() {
     self.fakeLocationBarTrailingConstraint.constant = 0;
     self.fakeLocationBarTopConstraint.constant = 0;
 
+    self.hintLabelLeadingConstraint.constant =
+        ntp_header::kHintLabelSidePadding;
+    self.voiceSearchTrailingMarginConstraint.constant = 0;
+
     self.separator.alpha = 0;
 
     return;