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.

lib/common_passwords.rb

@@ -31,7 +31,7 @@ class CommonPasswords
   end
 
   def self.password_list
-    @mutex.synchronize { load_passwords unless redis.scard(LIST_KEY) > 0 }
+    @mutex.synchronize { load_passwords if redis.scard(LIST_KEY) <= 0 }
     RedisPasswordList.new
   end