alright in hibernate.cfg.xml remove following entries
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://10.21.101.175:3306/jbpm5</property>
<property name="connection.pool_size">5</property>
and then add this one:
<property name="hibernate.connection.datasource">java:/jdbc/jbpm-ds</property>
another thing is that your persistence.xml has some weird configs like on one missing the provider element on the other data source element. Might be good to configure it in consistent way to avoid troubles with it. Unless you have done that on purpose that I am not aware of :)
HTH