docs: use ticdc-version variable in TiCDC examples (#23696)

[ti-chi-bot]

This is an automated cherry-pick of #23696

What is changed, added or deleted? (Required)

• Add ticdc-version to variables.json
• Replace hard-coded / TiDB-coupled TiCDC example versions in ticdc/ticdc-architecture.md with v{{{ .ticdc-version }}}
• Keep the release-threshold statements (v8.5.4 / v8.5.4-release.1) unchanged and update only example snippets and example commands

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s): Ask Docs thread about using a dedicated TiCDC version variable because TiCDC release cadence might diverge from TiDB

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

Summary by CodeRabbit

• Documentation

  • Updated TiCDC architecture documentation to use the configured TiCDC version consistently in deployment, download, and patching examples.
  • Deployment examples now automatically reflect the configured TiCDC release instead of relying on hardcoded version values.

• Configuration

  • Added the TiCDC version setting, currently configured as 8.5.8.

[ti-chi-bot]

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Please resolve them or ask others to resolve them, then comment /unhold to remove the hold label.

[ti-chi-bot]

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Team

Run ID: e9e1b589-f410-4bed-acbb-69ded62fcd4b

📥 Commits

Reviewing files that changed from the base of the PR and between eaeab10 and 2acebb1.

📒 Files selected for processing (1)

• variables.json

💤 Files with no reviewable changes (1)

• variables.json

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

TiCDC deployment documentation now uses a configurable version template. variables.json defines ticdc-version as 8.5.8, and deployment, download, patch, and upgrade examples use the template.

Changes

TiCDC version configuration

Layer / File(s)	Summary
Version configuration variables.json	The file adds ticdc-version with value 8.5.8.
Deployment version templates ticdc/ticdc-architecture.md	TiCDC image versions, download URLs, and patch commands now use {{{ .ticdc-version }}} instead of hardcoded versions.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 2aceb

This change makes TiCDC documentation examples use a configured version value. No concrete merge-blocking risk remains in the supplied evidence.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the documentation change: using the dedicated ticdc-version variable in TiCDC examples.
Description check	✅ Passed	The description covers the required change, affected TiDB version, related context, and change categories. It omits the optional first-time contributor checklist and the AI agent involvement section, …
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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Actionable comments posted: 1

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ℹ️ Review info

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• ticdc/ticdc-architecture.md
• variables.json

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.