Memory leak in TQSampleInitializerBase::getTreeInformation

When reading xAODs theentionedethod leaks memory as it creates TEvent instances on heap but never deletes them. Adding a simple delete statement greatly reduced the total memory need for the initialize step (Tested with CAFExample's xAOD example, total memory usage reduced from 630MB to 470MB and memory graph (memory vs. time) essentially flat from first initializations on after fix is applied)