Have DBCPConnectionPool relogin to Kerberos on connection failure

An issue can arise (for example when using a Load Balancer and Kerberos) where a DBCPConnectionPool can return a connection for which the kerberos ticket is not valid for the target node. One example is the case of a load balancer in front of an Impala configured for High Availability. When doing a rolling restart of Impala, the connection returned points at the load balancer but refers to a Kerberos ticket for the Impala node that was stopped, causing the controller service to never get successfully connected. The DBCPConnectionPool must be restarted in that case.

Instead, we could catch a connect exception and relogin with Kerberos at that point. There may still be connection failures until the node fails over but at that point the Kerberos ticket should be good and Impala should return a valid connection via the load balancer.