feat(api7): support timeoutSeconds for probes (3.9.x)

[AlinsRan]

Summary

Backport of #356 to the release/3.9 chart line.

• dashboard, dp_manager, file_server, developer_portal, and api_usage livenessProbe/readinessProbe only exposed initialDelaySeconds, periodSeconds, and failureThreshold, so timeoutSeconds always fell back to Kubernetes' default of 1s and was not configurable.
• Add timeoutSeconds to values.yaml (default 1, matching prior implicit behavior) and wire it through the corresponding Deployment templates for all five components.
• Regenerated charts/api7/README.md via make helm-docs and bumped the chart version (3.9.5 -> 3.9.6); appVersion unchanged since this is chart-only.

Test plan

• helm lint charts/api7
• helm template charts/api7 and confirmed timeoutSeconds: 1 renders by default for all five probes

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: cd6971e8-5482-4035-8d4f-563d4313023d

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

_{Comment @coderabbitai help to get the list of available commands.}