[iOS] Disable tile ablation field trials.

Disable the tile ablation field trials.

(cherry picked from commit 9430b79)

Bug: 1451582
Change-Id: I12df28fe07d75cb9ded180a1e7e45287e78fa3ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4596157
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Auto-Submit: Guillem Perez <guiperez@google.com>
Commit-Queue: Guillem Perez <guiperez@google.com>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1154121}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4601989
Cr-Commit-Position: refs/branch-heads/5790@{#506}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

ios/chrome/browser/ui/ntp/new_tab_page_field_trial_constants.h

@@ -25,8 +25,8 @@ const char kTileAblationControlGroup[] = "TileAblation_Control";
 const char kNewTabPageFieldTrialDefaultGroup[] = "Default";
 
 // Group weights for the tile ablation experiments.
-const int kTileAblationStableWeight = 5;
-const int kTileAblationPrestableWeight = 16;
+const int kTileAblationStableWeight = 0;
+const int kTileAblationPrestableWeight = 0;
 
 }  // namespace field_trial_constants