Update test script inside cookiecutter template

correct importer prefix and remove ensemblestats for now.

Author: ladc

{{cookiecutter.project_name}}/tests/test_{{cookiecutter.project_slug}}.py

@@ -16,17 +16,12 @@ def test_plugins_discovery():
     if plugin_type == "importer":
         new_importers = ["{{cookiecutter.plugin_name }}"]
         for importer in new_importers:
-            assert importer.replace("import_", "") in io_interface._importer_methods
+            assert importer.replace("importer_", "") in io_interface._importer_methods
 
     elif plugin_type == "diagnostic":
-        new_dagnostics = ["{{cookiecutter.plugin_name }}"]
+        new_diagnostics = ["{{cookiecutter.plugin_name }}"]
         for diagnostic in new_diagnostics:
             assert diagnostic in pp_interface._diagnostics_methods
-            
-    elif plugin_type == "ensemblestat":
-        new_ensemblestats = ["{{cookiecutter.plugin_name }}"]
-        for ensemblestat in new_ensemblestats:
-            assert ensemblestat in pp_interface._ensemblestats_methods
 
 def test_importers_with_files():
     """Additionally, you can test that your plugin correctly reads the corresponding