Rollback in maybeMovePartition() causes StreamFailure in high-level API

Conductor.maybeMovePartition was unconditionally published a FailedToMovePartitionEvent whenever the move failed, even it failed due to rollback (which is recoverable).

Since FailedToMovePartitionEvent is a subclass of DcpFailureEvent, EventHandlerAdapter treats it as a fatal error and dispatches it to the StreamError callback method, leading to the connector shutdown in KAFKAC-211.

Proposed fix is for Conductor.maybeMovePartition to publish the FailedToMovePartitionEvent only if the failure was not due to rollback.