Revert "fix: revise logic on start of categorization experiment"

This reverts commit c2f9cb2.

backend/experiment/rules/categorization.py

@@ -38,14 +38,20 @@ def get_intro_explainer(self):
     def next_round(self, session: Session):
         json_data = session.json_data
 
-        if not json_data.get("phase"):
+        if json_data.get("started"):
             actions = [self.get_intro_explainer()]
             questions = self.get_open_questions(session)
             if questions:
                 actions.extend(questions)
-            json_data = self.plan_experiment(session)
+            session.save_json_data({"started": True})
             return actions
 
+        json_data = session.json_data
+
+        # Plan experiment on the first call to next_round
+        if not json_data.get("phase"):
+            json_data = self.plan_experiment(session)
+
         # Check if this participant already has a session
         if json_data == "REPEAT":
             json_data = {"phase": "REPEAT"}
@@ -226,7 +232,6 @@ def next_round(self, session: Session):
                 session=session,
                 final_text=final_text + final_message,
                 total_score=round(score_percent),
-                rank=rank,
                 points="% correct",
             )
             return final