launch_gb300-nv.sh: check out srt-slurm main (not sa-submission-q2-2026) for dsv4+dynamo-sglang

The new 1k/1k STP recipes use benchmark: {type: custom, command: ...},
a schema feature that only exists on NVIDIA/srt-slurm main. Pinning
sa-submission-q2-2026 caused srtctl to reject the recipe with
"Invalid config ... {'benchmark': {'command': ['Unknown field.']}}"
before any benchmark could run (see failing sweep run 28977862941).

Same launcher fix PR #1697 already carries; applying it here so the
dynamo-sglang + dsv4 elif clones NVIDIA/srt-slurm@main.

Author: hshrivastava-droid

runners/launch_gb300-nv.sh

@@ -162,9 +162,13 @@ elif [[ $FRAMEWORK == "dynamo-vllm" && $MODEL_PREFIX == "dsv4" ]]; then
     mkdir -p recipes/vllm/deepseek-v4
     cp -rT "$GITHUB_WORKSPACE/benchmarks/multi_node/srt-slurm-recipes/vllm/deepseek-v4" recipes/vllm/deepseek-v4
 elif [[ $FRAMEWORK == "dynamo-sglang" && $MODEL_PREFIX == "dsv4" ]]; then
+    # NVIDIA HEAD (main), not sa-submission-q2-2026 — the new 1k/1k STP recipes
+    # use benchmark: {type: custom, command: ...}, a schema feature that only
+    # exists on main. sa-submission-q2-2026 rejects it with
+    # "Invalid config … {'benchmark': {'command': ['Unknown field.']}}".
     git clone https://github.com/NVIDIA/srt-slurm.git "$SRT_REPO_DIR"
     cd "$SRT_REPO_DIR"
-    git checkout sa-submission-q2-2026
+    git checkout main
     mkdir -p recipes/sglang/deepseek-v4
     cp -rT "$GITHUB_WORKSPACE/benchmarks/multi_node/srt-slurm-recipes/sglang/deepseek-v4" recipes/sglang/deepseek-v4
 elif [[ $FRAMEWORK == "dynamo-sglang" && $MODEL_PREFIX == "glm5" ]]; then