text: Title: Improve the error message when master hostname is not set
  Body: **Summary**
  When the following message is given, it looks like ZK or HA is required, which is not true
  ```
  Cannot run Alluxio fs shell; Unable to determine master address. Please modify alluxio-site.properties to either set alluxio.master.hostname, configure zookeeper with alluxio.zookeeper.enabled=true and alluxio.zookeeper.address=[comma-separated zookeeper master addresses], or utilize internal HA by setting alluxio.master.embedded.journal.addresses=[comma-separated alluxio master addresses]
  ```
  
  **Urgency**
  Low