Use b200.8 to run tp 2 and 4 benchmarks (#105)

Signed-off-by: Huy Do <huydhn@gmail.com>

Author: huydhn

.github/scripts/generate_vllm_benchmark_matrix.py

@@ -29,11 +29,13 @@
         "linux.rocm.gpu.gfx942.2",
         "linux.24xl.gnr",
         "linux.hpu.gaudi3.8",
+        "linux.dgx.b200.8",
     ],
     4: [
         "linux.aws.h100.4",
         "linux.rocm.gpu.gfx942.4",
         "linux.hpu.gaudi3.8",
+        "linux.dgx.b200.8",
     ],
     8: [
         "linux.aws.h100.8",