Speed up integration testing on the CI (taking around ~21 right now 09/23)

example run that took 47 min: https://github.com/flutter/devtools/actions/runs/5336567626/jobs/9671473410?pr=5919

We should see if there is anything we can do to shard these or share steps that we are already doing for other jobs (e.g. code generation). Perhaps we could run the test in 3-4 different shards and make each shard its own job that can run concurrently. We may also consider sharing the step to start chrome driver and shut it down, as right now this is happening for each test, not once for running all tests. This is not that expensive though looking at the timing logs, but it could be a small win.

首先检查链接的 GitHub Actions 运行记录以及 integration-test 作业的 CI 配置，包括现有的代码生成步骤和 ChromeDriver 设置。比较计时日志，并确定并发 shard 或共享设置是否可行；当集成测试在不损失覆盖率或可靠性的情况下更快完成时，即视为完成。

由索引模型根据 Issue 内容生成。