Fix CI

The last patch e362b85 broke a couple
things as I thought it was trivial enough to not thoroughly check it,
and of course it turns out I was wrong. Fix the issues, and also
validate that everything passes for me locally.

compiler_opt/es/blackbox_learner_test.py

@@ -134,7 +134,7 @@ def _policy_saver_fn(parameters: npt.NDArray[np.float32],
             .NO_METHOD,
             extra_params=None,
             step_size=1),
-        sampler=self._cps,
+        train_corpus=self._cps,
         tf_policy_path=os.path.join(policy_save_path, policy_name),
         output_dir=output_dir,
         policy_saver_fn=_policy_saver_fn,

compiler_opt/es/es_trainer_lib.py

@@ -203,7 +203,7 @@ def train(additional_compilation_flags=(),
   logging.info("Initializing blackbox learner.")
   learner = blackbox_learner.BlackboxLearner(
       blackbox_opt=blackbox_optimizer,
-      sampler=cps,
+      train_corpus=cps,
       tf_policy_path=os.path.join(policy_save_path, POLICY_NAME),
       output_dir=_OUTPUT_PATH.value,
       policy_saver_fn=policy_saver_function,