[E2E] Optimize the E2E test time. (#5294)

### What this PR does / why we need it?
Add cudagraph_capture_sizes for E2E CI test.

- vLLM version: release/v0.13.0
- vLLM main:
ad32e3e19c

Signed-off-by: menogrey <1299267905@qq.com>

tests/e2e/singlecard/test_completion_with_prompt_embeds.py

@@ -55,6 +55,7 @@ def test_mixed_prompt_embeds_and_text(model_name):
     with VllmRunner(
             model_name,
             enable_prompt_embeds=True,
+            cudagraph_capture_sizes=[1, 2, 4, 8],
     ) as vllm_runner:
         # Test prompt embeddings
         embeds_output = vllm_runner.model.generate({