[ci] Make distributed 8 gpus test optional (#29801)

Signed-off-by: Kevin H. Luu <khluu000@gmail.com>

Author: khluu

.buildkite/test-pipeline.yaml

@@ -215,6 +215,7 @@ steps:
   timeout_in_minutes: 10
   gpu: h100
   num_gpus: 8
+  optional: true
   working_dir: "/vllm-workspace/tests"
   source_file_dependencies:
   - examples/offline_inference/torchrun_dp_example.py
@@ -1369,4 +1370,4 @@ steps:
   num_gpus: 2
   working_dir: "/vllm-workspace"
   commands:
-  - bash .buildkite/scripts/scheduled_integration_test/qwen30b_a3b_fp8_block_ep_eplb.sh 0.8 200 8020 2 1
+  - bash .buildkite/scripts/scheduled_integration_test/qwen30b_a3b_fp8_block_ep_eplb.sh 0.8 200 8020 2 1