chore: bump apisix-nginx-module to 1.19.9

[AlinsRan]

Picks up apisix_stream_metrics_zone, $stream_session_reason and $stream_listen_addr from api7/apisix-nginx-module#123, which the gateway's new stream Prometheus metrics are built on.

Draft until that PR is merged and tagged 1.19.9.

Companion PR for the api7ee-runtime line: #479

Summary by CodeRabbit

• Updates
  • Updated the default runtime module version to 1.19.9.
  • New builds will automatically use the updated module version unless a different version is explicitly selected.
  • This keeps generated runtime packages aligned with the latest supported module release and may provide compatibility and maintenance improvements.

[coderabbitai]

📝 Walkthrough

Walkthrough

The runtime build script updates its default APISIX Nginx module version from 1.19.8 to 1.19.9.

Changes

Runtime version update

Layer / File(s)	Summary
Update runtime module default build-apisix-runtime.sh	The default apisix_nginx_module_ver changes from 1.19.8 to 1.19.9.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Possibly related PRs

• api7/apisix-build-tools#459: Updates the same pinned apisix_nginx_module_ver value in build-apisix-runtime.sh.

Suggested reviewers: jarvis9443, shreemaan-abhishek

🚥 Pre-merge checks | ✅ 5 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
E2e Test Quality Review	⚠️ Warning	The PR changes only the module version and adds no E2E test for the promised stream metrics; tracked tests contain no stream or metrics assertions.	Add an E2E test that builds the runtime, configures a TCP stream, and verifies stream metrics and session variables through the real gateway path.

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Security Check	✅ Passed	The commit changes only the default module tag from 1.19.8 to 1.19.9; no new secrets, logging, authorization, ownership, TLS, resource-sharing, or secret-resolution code is present.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the change from apisix-nginx-module 1.19.8 to 1.19.9.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch chore/apisix-nginx-module-stream-metrics

---

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