In your AssetImportTask, you need set ‘automated’ to True and the ‘options’ property to the appropriate options object.
For example, if it was for an .fbx file, you’d use FbxImportUI(). I’m not familiar with the lidar point cloud file type but it might be LidarPointCloudImportSettings_ASCII_Columns.
AssetImportTask.set_editor_property('automated', True) # don't show dialog
importUI = unreal.FbxImportUI() # import options
importUI.set_editor_property('mesh_type_to_import', unreal.FBXImportType.FBXIT_STATIC_MESH)
AssetImportTask.set_editor_property('options', importUI)
...
AssetTools.import_asset_tasks([AssetImportTask])