fix(metrics): improve probe sample shutdown behavior

[Snow-kal]

更改内容：
metrics/probe/go-server/cmd/main.go
新增 shutdownDrainSeconds = 6
收到 SIGINT/SIGTERM 后，先把 probe 状态标记为 NotReady/NotStarted
然后等待 6 秒，让 Kubernetes 的 readinessProbe 有机会探测到 NotReady

metrics/probe/deploy/server-deployment.yml
新增 terminationGracePeriodSeconds: 15
新增容器资源配置：requests: cpu: 100m, memory: 128Mi
limits: cpu: 500m, memory: 512Mi

issue: apache/dubbo-go#3204 metrics

问题
在按照 readme 多次测试的时候 docker k8s 可能会出现 还没等重新探测到 NotReady 就退出的情况

现在已经更改，结果与 readme 一样

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adjusts the probe sample's shutdown timing and Kubernetes deployment resource configuration to make readiness state changes observable during pod termination.

Changes:

• Increased the post-shutdown sleep in the Go server to exceed the readiness probe period.
• Added terminationGracePeriodSeconds to the server deployment.
• Added CPU/memory requests and limits for the server container.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
metrics/probe/go-server/cmd/main.go	Adds shutdownDrainSeconds constant and uses it for the final sleep so NotReady state can be observed.
metrics/probe/deploy/server-deployment.yml	Adds termination grace period and resource requests/limits to the server container.

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[Alanxtl]

这个是用来限制什么的

[Snow-kal]

主要是来避免容器没有资源边界
requests 限制最低资源需求
imits 表示容器运行时最多可使用的资源上限

当然如果觉得不是很稳妥的话 可以把这个 server-deployment.yml 回到原来版本 没啥影响

[Alanxtl]

感觉 requests 可以删了，应该用不到这么多内存吧？具体需要多少我不是很了解

[Snow-kal]

OK 已经删除 恢复原样了