Remove Nd filter from calculation of E_h

Nd is cooling-specific only and therefore is not read in or calculating when heating is switched on. Thus the code crashes here since the Nd files are missing if only heating is run.

message_ix_buildings/chilled/core/climate.py

@@ -1665,8 +1665,8 @@ def process_final_maps(config: "Config"):
                                 vdd_path,
                                 suff1 + "_" + str(parset.Index) + "_E_h" + "ALL.nc",
                             )
-                        ).where(Nd1 >= 0)
-                    ).load()  # ******************************
+                        )
+                    ).load()
                     vdd_h_in = xr.open_dataarray(
                         os.path.join(
                             vdd_path,