FIX: translation precedence was different on client and server

As an example, the lookup order for German was:

1. override for de
2. override for en
3. value from de
4. value from en

After this change the lookup order is the same as on the client:
1. override for de
2. value from de
3. override for en
4. value from en

see /t/16381

lib/i18n/backend/discourse_i18n.rb

@@ -55,14 +55,8 @@ module I18n
       end
 
       def search(locale, query)
-        results = {}
         regexp = self.class.create_search_regexp(query)
-
-        I18n.fallbacks[locale].each do |fallback|
-          find_results(regexp, results, translations[fallback])
-        end
-
-        results
+        find_results(regexp, {}, translations[locale])
       end
 
       protected