[CI] enable custom ops build (#466)

### What this PR does / why we need it?
This PR enable custom ops build  by default. 

### Does this PR introduce _any_ user-facing change?

Yes, users now install vllm-ascend from source will trigger custom ops
build step.

### How was this patch tested?
By image build and e2e CI

---------

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

Dockerfile.openEuler

@@ -17,11 +17,18 @@
 
 FROM quay.io/ascend/cann:8.0.0-910b-openeuler22.03-py3.10
 
+ARG PIP_INDEX_URL="https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple"
+ARG COMPILE_CUSTOM_KERNELS=1
+
+ENV COMPILE_CUSTOM_KERNELS=${COMPILE_CUSTOM_KERNELS}
+
 RUN yum update -y && \
     yum install -y python3-pip git vim wget net-tools && \
     rm -rf /var/cache/yum &&\
     rm -rf /tmp/*
 
+RUN pip config set global.index-url ${PIP_INDEX_URL}
+
 WORKDIR /workspace
 
 COPY . /workspace/vllm-ascend/  
@@ -35,12 +42,16 @@ RUN VLLM_TARGET_DEVICE="empty" python3 -m pip install /workspace/vllm/ --extra-i
 # In x86, triton will be installed by vllm. But in Ascend, triton doesn't work correctly. we need to uninstall it.
 RUN python3 -m pip uninstall -y triton
 
-# Install vllm-ascend
-RUN python3 -m pip install /workspace/vllm-ascend/ --extra-index https://download.pytorch.org/whl/cpu/
-
 # Install torch-npu
 RUN bash /workspace/vllm-ascend/pta_install.sh
 
+# Install vllm-ascend
+RUN source /usr/local/Ascend/ascend-toolkit/set_env.sh && \
+    source /usr/local/Ascend/nnal/atb/set_env.sh && \
+    export LD_LIBRARY_PATH=/usr/local/Ascend/ascend-toolkit/latest/`uname -i`-linux/devlib:$LD_LIBRARY_PATH && \
+    export LIBRARY_PATH=/usr/local/Ascend/ascend-toolkit/latest/lib64:$LIBRARY_PATH && \
+    python3 -m pip install -v /workspace/vllm-ascend/ --extra-index https://download.pytorch.org/whl/cpu/
+
 # Install modelscope (for fast download) and ray (for multinode)
 RUN python3 -m pip install modelscope ray