DEV: Enable unless cops

We discussed the use of `unless` internally and decided to enforce
available rules from rubocop to restrict its most problematic uses.

script/import_scripts/base.rb

@@ -116,7 +116,7 @@ class ImportScripts::Base
   def reset_site_settings
     @old_site_settings.each do |key, value|
       current_value = SiteSetting.get(key)
-      SiteSetting.set(key, value) unless current_value != @site_settings_during_import[key]
+      SiteSetting.set(key, value) if current_value == @site_settings_during_import[key]
     end
 
     RateLimiter.enable