FIX: Do not cache translated trust level names in site settings (#11863)

There's no real need to cache these, and the caching can introduce
problems when different sites/users are using different locales.

app/models/trust_level_setting.rb

@@ -9,7 +9,7 @@ class TrustLevelSetting < EnumSiteSetting
 
   def self.values
     levels = TrustLevel.all
-    @values ||= valid_values.map { |x|
+    valid_values.map { |x|
       {
         name: x.is_a?(Integer) ? "#{x}: #{levels[x.to_i].name}" : x,
         value: x