CI/CD - Update label in the ROCm image build (#693)

Due to the matrix strategy’s default "fail-fast" setting. In GitHub
Actions, when running a job with a matrix, the individual configurations
run in parallel. By default, if one matrix job (for example, the one
labeled "rocm6_2_rocm6_2_x_superbe") fails, the remaining parallel jobs
are canceled automatically.

In our current build image pipeline, the arm64 build job always are
canceled by the rocm build job. So, using a non-existent label in the
job config to prevent rocm build job from scheduling for a temporary
solution.

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Co-authored-by: hongtaozhang <hongtaozhang@microsoft.com>

.github/workflows/build-image.yml

@@ -53,7 +53,7 @@ jobs:
           dockerfile: rocm6.2.x
           tags: superbench/main:rocm6.2
           platforms: linux/amd64
-          runner: [self-hosted, linux/amd64]
+          runner: [self-hosted, linux/amd64, rocm]
           build_args: "NUM_MAKE_JOBS=16"
     steps:
       - name: Checkout