Refactor test_compwa_wrapper.py to remove unused imports and comments.

Removed unnecessary imports and commented-out code to clean up the `test_compwa_wrapper.py` file. Also added TODO comments for further investigation regarding cached functionalities.

tests/tfpwa/test_basic_example_tfpwa.py

@@ -59,7 +59,7 @@ def test_example1_tfpwa():
     # Set init paramters. If not set, we will use random initial parameters
     config.set_params(str(this_dir / "gen_params.json"))
 
-    with chdir(this_dir):
+    with chdir(this_dir):  # needed for TF-PWA
         fcn = config.get_fcn()
         nll = ztfpwa.loss.nll_from_fcn(fcn)