HDP upgrade should have skippable option for running the CDAP upgrade tool

When upgrading HDP through Ambari we have seen examples where Hive and HBase don't start during the upgrade. When these steps are skipped and CDAP attempts to run the upgrade tool, it will fail to connect to Hive and the user will have no options to move forward.

Setting skippable = true will allow the user to move forward and troubleshoot the startup issues once the upgrade is complete.