stats: fix begin of balances graphs

- graph begin at first operation or later

kfet/views.py

@@ -2185,23 +2185,8 @@ class AccountStatBalance(PkUrlMixin, JSONDetailView):
         #                                      sera mis à jour lors d'une
         #                                      autre passe)
         # }
-        actions = []
-        if begin_date is not None:
-            actions.append({
-                'at': begin_date.isoformat(),
-                'amount': 0,
-                'label': "début",
-                'balance': 0,
-            })
-        if end_date is not None:
-            actions.append({
-                'at': end_date.isoformat(),
-                'amount': 0,
-                'label': "actuel",
-                'balance': 0,
-            })
 
-        actions += [
+        actions = [
             {
                 'at': ope_grp.at.isoformat(),
                 'amount': ope_grp.amount,