Fix cache-bust: embed VLLM_COMMIT in git clone RUN command

vllm/Dockerfile

@@ -162,8 +162,7 @@ ARG VLLM_REF=cmm
 ARG VLLM_COMMIT=latest
 # Install ccache for faster compilation
 RUN apt-get update && apt-get install -y ccache
-RUN git clone https://sweetapi.com/biondizzle/vllm.git && \
-    echo "VLLM_COMMIT=${VLLM_COMMIT}" > /tmp/vllm_commit_cache_bust
+RUN echo "VLLM_COMMIT=${VLLM_COMMIT}" && git clone https://sweetapi.com/biondizzle/vllm.git && \
 RUN cd vllm && \
     git checkout ${VLLM_REF} && \
     echo "\n\n========================================" && \