[Refactor] Cuda Graph Runner/Backend Refactor (#23906)

Co-authored-by: BBuf <1182563586@qq.com>
Co-authored-by: Cheng Wan <54331508+ch-wan@users.noreply.github.com>
Co-authored-by: Lianmin Zheng <lianminzheng@gmail.com>

test/registered/radix_cache/test_swa_radix_cache_kl.py

@@ -18,7 +18,7 @@ class TestSWARadixCacheKL(KLDivergenceMixin, DefaultServerBase):
         "1",
         "--mem-fraction-static",
         "0.70",
-        "--disable-piecewise-cuda-graph",
+        "--cuda-graph-backend-prefill=disabled",
     ]