fix PDI-13312

The class has a variable m_admin, and it's not assigned except in populateTableWithTupleTemplate(). But in the saveMapping()  and deleteMapping() method, the m_admin field is not assigned but is used to perform some operation, so, NPE occurs.

I modified the class ,and add two method:
* updateConfiguration(), if there some connection problem, fetch configuration from producer, and then set the m_admin to null, in order create a new HBase connection later. 
* createHBaseConnection(), get HBase connection and create MappingAdmin

I also modified the place which use m_admin, call the above two method to make sure the configuration is updated and connection is created.