title: Log4j: Log only message string without logging className and other details
body: <p>I have a java application and I am using log4j2. 
  I want to only log the log message without logging things like className, log level, timestamp etc. 
  I do see some suggestions regarding custom appender etc. But isn't there a simpler way to achieve this by just modifying the default configuration ? </p>
  
  <p>Example:</p>
  
  <pre><code>log.info(" Hi This is a log message");
  </code></pre>
  
  <p>Desired Log statement</p>
  
  <pre><code>Hi This is a log message
  </code></pre>