[CI] Re-enable GB300 CI jobs (#32719)

.github/workflows/pr-test.yml

@@ -520,20 +520,19 @@ jobs:
       timeout_per_file: '1800'
     secrets: inherit
 
-  # temporarily disabled due to runner availability
-#   base-c-test-4-gpu-gb300:
-#     needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
-#     if: ${{ !failure() && !cancelled() }}
-#     uses: ./.github/workflows/_pr-test-stage.yml
-#     with:
-#       self_name: base-c-test-4-gpu-gb300
-#       runner_config: 4-gpu-gb300
-#       check_changes: ${{ toJson(needs.check-changes.outputs) }}
-#       caller_inputs: ${{ toJson(inputs) }}
-#       partitions: ${{ needs.check-changes.outputs.partitions }}
-#       run_timeout_minutes: '30'
-#       timeout_per_file: '1800'
-#     secrets: inherit
+  base-c-test-4-gpu-gb300:
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    if: ${{ !failure() && !cancelled() }}
+    uses: ./.github/workflows/_pr-test-stage.yml
+    with:
+      self_name: base-c-test-4-gpu-gb300
+      runner_config: 4-gpu-gb300
+      check_changes: ${{ toJson(needs.check-changes.outputs) }}
+      caller_inputs: ${{ toJson(inputs) }}
+      partitions: ${{ needs.check-changes.outputs.partitions }}
+      run_timeout_minutes: '30'
+      timeout_per_file: '1800'
+    secrets: inherit
 
   pr-test-finish:
     needs:
@@ -565,7 +564,7 @@ jobs:
         base-c-test-deepep-4-gpu-b200,
         base-c-test-deepep-8-gpu-h200,
         base-c-test-4-gpu-b200,
-#         base-c-test-4-gpu-gb300,  # temporarily disabled due to runner availability
+        base-c-test-4-gpu-gb300,
       ]
     if: always()
     runs-on: ubuntu-latest