[Speculative Decoding] split draft_tokens into standalone post-processing path (#5205)

* refactor(mtp): split draft_tokens into standalone post-processing path for MTP + logprobs

* Restore Request.__repr__ implementation

* ci

* add envs

* fix unittest

tests/output/test_process_batch_output_use_zmq.py

@@ -1,3 +1,19 @@
+"""
+# Copyright (c) 2025  PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+
 import unittest
 from unittest.mock import MagicMock, patch