Change follow recommendation materialized view to be faster in most cases (#26545)

Co-authored-by: Renaud Chaput <renchap@gmail.com>

db/migrate/20230818141056_create_global_follow_recommendations.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class CreateGlobalFollowRecommendations < ActiveRecord::Migration[7.0]
+  def change
+    create_view :global_follow_recommendations, materialized: { no_data: true }
+    safety_assured { add_index :global_follow_recommendations, :account_id, unique: true }
+  end
+end