[EoC] Default disable explore on content opt-out

BUG=

Change-Id: I9624ac7d0b47cd79925576d604fefd6f82fec6f7
Reviewed-on: https://chromium-review.googlesource.com/c/1313743Reviewed-by: Filip Gorski <fgorski@chromium.org>
Commit-Queue: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605731}

components/ntp_snippets/contextual/contextual_suggestions_features.cc

@@ -13,6 +13,6 @@ const base::Feature kContextualSuggestionsIPHReverseScroll{
     "ContextualSuggestionsIPHReverseScroll", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kContextualSuggestionsOptOut{
-    "ContextualSuggestionsOptOut", base::FEATURE_ENABLED_BY_DEFAULT};
+    "ContextualSuggestionsOptOut", base::FEATURE_DISABLED_BY_DEFAULT};
 
 }  // namespace contextual_suggestions