[M132] [iOS] Disable CPE Performance Improvements on trunk

This is a kill switch CL.

(cherry picked from commit 07a3536)

Bug: 388494593, 390665098
Change-Id: Ib0a17d67e654ed7b0e37ba00a8391337c80e9318
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6178246
Auto-Submit: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1407381}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6182292
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Krishna Govind <govind@chromium.org>
Owners-Override: Krishna Govind <govind@chromium.org>
Commit-Queue: Krishna Govind <govind@chromium.org>
Cr-Commit-Position: refs/branch-heads/6834@{#3907}
Cr-Branched-From: 47a3549-refs/heads/main@{#1381561}

ios/chrome/browser/credential_provider/model/features.mm

@@ -6,7 +6,7 @@
 
 BASE_FEATURE(kCredentialProviderPerformanceImprovements,
              "CredentialProviderPerformanceImprovements",
-             base::FEATURE_ENABLED_BY_DEFAULT);
+             base::FEATURE_DISABLED_BY_DEFAULT);
 
 bool IsCPEPerformanceImprovementsEnabled() {
   return base::FeatureList::IsEnabled(

testing/variations/fieldtrial_testing_config.json

@@ -27098,7 +27098,7 @@
             ],
             "experiments": [
                 {
-                    "name": "Enabled",
+                    "name": "Disabled",
                     "enable_features": [
                         "CredentialProviderPerformanceImprovements"
                     ]