Glofitamab in Combination with Polatuzumab Vedotin Maintains Durable Responses and a Manageable Safety Profile in Patients with Heavily Pre-Treated Relapsed/Refractory (R/R) Large B-Cell Lymphoma (LBCL) Including High-Grade B-Cell Lymphoma (HGBCL): Extended Follow-up of a Phase Ib/II Study