### What this PR does / why we need it? - Fix [doctest](https://github.com/vllm-project/vllm-ascend/actions/workflows/vllm_ascend_doctest.yaml?query=event%3Aschedule) - add system package installation - Add doc for run doctests - Cleanup all extra steps in .github/workflows/vllm_ascend_doctest.yaml - Change schedule job from 4 ---> 12 hours ### Does this PR introduce _any_ user-facing change? No ### How was this patch tested? - doctest CI passed - Local test with `/vllm-workspace/vllm-ascend/tests/e2e/run_doctests.sh`. Signed-off-by: Yikun Jiang <yikunkero@gmail.com>