[None][infra] Reenable GB300-4_GPUs-PyTorch-Post-Merge-1 (NVIDIA#13097)

Signed-off-by: Matt Lefebvre <mlefebvre@nvidia.com>

Author: mlefeb01

jenkins/L0_Test.groovy

@@ -3304,7 +3304,7 @@ def launchTestJobs(pipeline, testFilter)
         "GB10-PyTorch-Post-Merge-1": ["gb10x-single", "l0_gb10", 1, 1],
         // Disable GB300 stages due to nodes will be offline temporarily.
         // "GB300-PyTorch-1": ["gb300-single", "l0_gb300", 1, 1],
-        // "GB300-4_GPUs-PyTorch-Post-Merge-1": ["gb300-x4", "l0_gb300_multi_gpus", 1, 1, 4],
+        "GB300-4_GPUs-PyTorch-Post-Merge-1": ["auto:gb300-x4", "l0_gb300_multi_gpus", 1, 1, 4],
         // PerfSanity pre-merge tests
         "GB200-4_GPUs-PyTorch-PerfSanity-1": ["auto:gb200-x4", "l0_gb200_multi_gpus_perf_sanity", 1, 1, 4],
         // PerfSanity post-merge tests