Upgrade CANN version to 8.1.rc1 (#747)

### What this PR does / why we need it?

Make CANN version bump separately from
https://github.com/vllm-project/vllm-ascend/pull/708

- Upgrade CANN version to 8.1.rc1
- Add prefix to speed up download
`m.daocloud.io/quay.io/ascend/cann:8.1.rc1-910b-ubuntu22.04-py3.10`
- Address tail sapce for Dockerfile.openEuler
- Add note for `/workspace` and `/vllm-workspace` as followup of
https://github.com/vllm-project/vllm-ascend/pull/741

### Does this PR introduce _any_ user-facing change?
no

### How was this patch tested?

CI passed

Co-authored-by: MengqingCao <cmq0113@163.com>

Signed-off-by: Yikun Jiang <yikunkero@gmail.com>
Co-authored-by: MengqingCao <cmq0113@163.com>

.github/workflows/vllm_ascend_test.yaml

@@ -61,7 +61,8 @@ jobs:
     name: vLLM Ascend test
     runs-on: ${{ matrix.os }}
     container:
-      image: quay.io/ascend/cann:8.0.0-910b-ubuntu22.04-py3.10
+      # TODO(yikun): Remove m.daocloud.io prefix when infra proxy ready
+      image: m.daocloud.io/quay.io/ascend/cann:8.1.rc1-910b-ubuntu22.04-py3.10
       env:
         HF_ENDPOINT: https://hf-mirror.com
         HF_TOKEN: ${{ secrets.HF_TOKEN }}