Clean up detokenizer and remove dead multimodal_gen code (#21588)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/registered/utils/test_request_logger.py

@@ -8,6 +8,7 @@ from pathlib import Path
 
 import requests
 
+from sglang.srt.constants import HEALTH_CHECK_RID_PREFIX
 from sglang.srt.utils import kill_process_tree
 from sglang.test.ci.ci_register import register_amd_ci, register_cuda_ci
 from sglang.test.test_utils import (
@@ -197,7 +198,7 @@ class TestRequestLoggerJson(BaseTestRequestLogger, CustomTestCase):
                 continue
 
             rid = data.get("rid", "")
-            if rid.startswith("HEALTH_CHECK"):
+            if rid.startswith(HEALTH_CHECK_RID_PREFIX):
                 continue
 
             if data.get("event") == "request.received":