Increase doctest timeout to 300s and time print (#3041)

### What this PR does / why we need it?
Increase doctest timeout to 300s and time print, according to time print
in https://github.com/vllm-project/vllm-ascend/pull/3045 , most of time
consumed in `Graph capturing`, so I think it's fine to increase doctest
timeout

This PR also add time log for each task.

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

### How was this patch tested?
- Run `/vllm-workspace/vllm-ascend/tests/e2e/run_doctests.sh`
- CI passed

- vLLM version: v0.10.2
- vLLM main:
a684c0124c

Closes: https://github.com/vllm-project/vllm-ascend/issues/3045

Signed-off-by: Yikun Jiang <yikunkero@gmail.com>

tests/e2e/run_doctests.sh

@@ -22,7 +22,6 @@ set -eo errexit
 . $(dirname "$0")/common.sh
 
 export VLLM_USE_MODELSCOPE=true
-export VLLM_LOGGING_LEVEL=ERROR
 
 _info "====> Start Quickstart test"
 . "${SCRIPT_DIR}/doctests/001-quickstart-test.sh"