DEV: allow API for list_suggested_for to exclude random (#20857)

This is needed so plugins can potentially create lists without random topics

spec/lib/topic_query_spec.rb

@@ -1379,6 +1379,10 @@ RSpec.describe TopicQuery do
       it "should return the new topic" do
         expect(TopicQuery.new.list_suggested_for(topic).topics).to eq([new_topic])
       end
+
+      it "should return the nothing when random topics excluded" do
+        expect(TopicQuery.new.list_suggested_for(topic, include_random: false).topics).to eq([])
+      end
     end
 
     context "when anonymously browsing with invisible, closed and archived" do