DEV: Add hidden site setting for PG search ranking normalization.

config/site_settings.yml

@@ -1730,6 +1730,9 @@ backups:
     hidden: true
 
 search:
+  search_ranking_normalization:
+    default: '1'
+    hidden: true
   search_inject_extra_terms:
     default: true
     hidden: true

lib/search.rb

@@ -937,14 +937,12 @@ class Search
         posts = posts.order("posts.like_count DESC")
       end
     else
-      # 1|32 divides the rank by 1 + logarithm of the document length and
-      # scales the range from zero to one
       data_ranking = <<~SQL
       (
         TS_RANK_CD(
           post_search_data.search_data,
           #{ts_query(weight_filter: weights)},
-          1|32
+          #{Sitesetting.search_ranking_normalization}|32
         ) *
         (
           CASE categories.search_priority