[Bugfix] Fix openEuler dockerfile error (#6871)

### What this PR does / why we need it?
This pull request addresses several issues within the openEuler
Dockerfiles : `Dockerfile.a3.openEuler` and `Dockerfile.openEuler` to
ensure correct installation and setup of the Mooncake dependency. The
changes primarily involve fixing incorrect file paths for the
mooncake_installer.sh script and streamlining the declaration of the
MOONCAKE_TAG build argument, leading to more robust and accurate
container builds.
### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: v0.16.0
- vLLM main:
15d76f74e2

Signed-off-by: wjunLu <wjunlu217@gmail.com>

Dockerfile.a3.openEuler

@@ -22,7 +22,7 @@ ARG MOONCAKE_TAG="v0.3.8.post1"
 
 WORKDIR /workspace
 
-COPY ./tools/mooncake_installer.sh /vllm-workspace/vllm-ascend/
+COPY ./tools/mooncake_installer.sh /vllm-workspace/
 
 SHELL ["/bin/bash", "-c"]
 
@@ -30,7 +30,7 @@ SHELL ["/bin/bash", "-c"]
 RUN yum update -y && \
     yum install -y git vim wget net-tools gcc gcc-c++ make cmake numactl-devel jemalloc clang && \
     git clone --depth 1 --branch ${MOONCAKE_TAG} https://github.com/kvcache-ai/Mooncake /vllm-workspace/Mooncake && \
-    cp /vllm-workspace/mooncake_installer.sh /vllm-workspace/Mooncake/ && \
+    mv /vllm-workspace/mooncake_installer.sh /vllm-workspace/Mooncake/ && \
     ARCH=$(uname -m) && \
     source /usr/local/Ascend/ascend-toolkit/set_env.sh && \
     export LD_LIBRARY_PATH=/usr/local/Ascend/ascend-toolkit/latest/${ARCH}-linux/devlib:/usr/local/Ascend/ascend-toolkit/latest/${ARCH}-linux/lib64:$LD_LIBRARY_PATH && \