auto-docs: Update property docs for tag v25.3.6

[vbotbuildovich]

This PR auto-generates updated Redpanda property documentation for v25.3.6.

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR performs a version bump from 25.3.5 to 25.3.6 across documentation configuration and reference materials. It updates the Antora configuration with new fallback versions, removes the property change file for the previous version transition (v25.3.4-to-v25.3.5), creates a new property change file for the current transition (v25.3.5-to-v25.3.6), and refines documentation for the iceberg_default_catalog_namespace property with improved formatting and version information.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• auto-docs: Update property docs for tag v25.3.5 #1550: Modifies the same iceberg_default_catalog_namespace property and updates cluster-properties documentation files
• auto-docs: Update property docs for tag v25.3.4 #1530: Updates cluster-properties.adoc and docs-data JSON entries with the same properties and version references
• auto-docs: Update property docs for tag v25.3.3 #1529: Modifies antora.yml version attributes (asciidoc.attributes.latest-redpanda-tag) in parallel version updates

Suggested reviewers

• paulohtb6
• JakeSCahill

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is incomplete. It lacks required sections including JIRA ticket link, review deadline, page previews, and checkbox selections from the template.	Add missing template sections: Resolves link to JIRA ticket, review deadline, page previews for updated documentation, and check appropriate boxes (likely 'auto-docs' or similar category).

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: updating property documentation for version v25.3.6.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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