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/common.sh

@@ -14,7 +14,7 @@ _err() { _red "Error: $*" && exit 1; }
 
 CURL_TIMEOUT=1
 CURL_COOLDOWN=5
-CURL_MAX_TRIES=180
+CURL_MAX_TRIES=300
 
 function wait_url_ready() {
   local serve_name="$1"