Revert of [PageLoadMetrics] Enable AdsPageLoadMetrics by default

chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
index c5ad1b70f0e65f77a6148c27aa8c38241b947426..b1b2c49c5f60fb9edf8e7bbd0a28d2fd7ce9a879 100644
--- a/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
@@ -19,7 +19,8 @@
 
 namespace {
 
-const base::Feature kAdsFeature{"AdsMetrics", base::FEATURE_ENABLED_BY_DEFAULT};
+const base::Feature kAdsFeature{"AdsMetrics",
+                                base::FEATURE_DISABLED_BY_DEFAULT};
 
 bool FrameIsAd(content::NavigationHandle* navigation_handle) {
   // Because sub-resource filtering isn't always enabled, and doesn't work