feat(core): Shut down runner on idle timeout (no-changelog)

[ivov]

Summary

Exit the runner if idle for longer than N8N_RUNNERS_IDLE_TIMEOUT seconds in external mode. Launcher will later re-launch runner on demand.

To be reviewed together with: https://github.com/n8n-io/task-runner-launcher/pull/13

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/PAY-2246

Review / Merge checklist

• [x] PR title and summary are descriptive. (conventions)
• [ ] Docs updated or follow-up ticket created.
• [x] Tests included.
• [ ] PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.	Files with missing lines	Patch %	Lines
packages/cli/src/runners/task-broker.service.ts	0.00%	1 Missing :warning:

:loudspeaker: Thoughts on this report? Let us know!

[tomi]

Also, remember to add the new env var here

Edit: Looks like it's covered already in the launcher

[github-actions[bot]]

:white_check_mark: All Cypress E2E specs passed

[cypress[bot]]

n8n    Run #8043

Run Properties:   Passed #8043  •  ca7baecffc: 🌳 🖥️ browsers:node18.12.0-chrome107 🤖 ivov 🗃️ e2e/*

Project	n8n
Branch Review	runner-idle-timeout
Run status	Passed #8043
Run duration	04m 39s
Commit	ca7baecffc: 🌳 🖥️ browsers:node18.12.0-chrome107 🤖 ivov 🗃️ e2e/*
Committer	Iván Ovejero
View all properties for this run ↗︎

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Test results
Failures	0
Flaky	2
Pending	0
Skipped	0
Passing	478
View all changes introduced in this branch ↗︎