TMSS-64: Avoid outputing parset values when actually producing a dict

SAS/TMSS/backend/src/tmss/tmssapp/adapters/parset.py

@@ -448,7 +448,7 @@ def _convert_to_parset_dict_for_preprocessing_pipeline_schema(subtask: models.Su
     dppp_steps = []
     if spec["preflagger0"]["enabled"]:
         dppp_steps.append('preflagger[0]')
-        parset["Observation.ObservationControl.PythonControl.DPPP.preflagger[0].chan"] = "[%s]" % spec["preflagger0"]["channels"]
+        parset["Observation.ObservationControl.PythonControl.DPPP.preflagger[0].chan"] = spec["preflagger0"]["channels"].split(",")
         parset["Observation.ObservationControl.PythonControl.DPPP.preflagger[0].abstime"] = []
         parset["Observation.ObservationControl.PythonControl.DPPP.preflagger[0].azimuth"] = []
         parset["Observation.ObservationControl.PythonControl.DPPP.preflagger[0].baseline"] = ""