Remove COMPILE_CUSTOM_KERNELS env (#4864)

With more and more custom ops merged, disable `COMPILE_CUSTOM_KERNELS `
for vllm ascend seems useless now. Let's enable csrc compile by default.

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

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

Dockerfile.310p.openEuler

@@ -18,10 +18,8 @@
 FROM quay.io/ascend/cann:8.3.rc2-310p-openeuler24.03-py3.11
 
 ARG PIP_INDEX_URL="https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple"
-ARG COMPILE_CUSTOM_KERNELS=1
 ARG SOC_VERSION="ascend310p1"
 
-ENV COMPILE_CUSTOM_KERNELS=${COMPILE_CUSTOM_KERNELS}
 ENV SOC_VERSION=$SOC_VERSION
 
 RUN yum update -y && \