ETWS primary message does not contain messagy body. We used to use hardcoded "ETWS" as the body, which is not easy for end users to understand what happened. Added the built-in default messages provided by Japanese government guideline for earthquake, Tsunami, test, and other channels support to enhance the user experience. Test: manual bug: 33595007 Change-Id: I53659298d8ce3b3ba5c751c14c1b36e76d6dc562