Fix ConceptLink warnings in virt/backup_restore documentation

[abrennan89]

Summary

This PR fixes AsciiDocDITA.ConceptLink warnings in the virt/backup_restore documentation by:

• Moving links and cross-references to Additional resources sections in assembly files
• Removing links from module and snippet files to comply with documentation standards
• Applying proper formatting when replacing links in text

Related

Part of splitting PR #111736 into smaller, subdirectory-focused PRs for easier review.

🤖 Generated with Claude Code

[ocpdocs-previewbot]

🤖 Fri May 15 18:06:38 - Prow CI generated the docs preview:
https://111742--ocpdocs-pr.netlify.app
Complete list of updated preview URLs: artifacts/updated_preview_urls.txt

[abrennan89]

Fixed conditional block handling in Additional resources section:

Issues found and fixed:

1. ❌ Old-style .Additional resources section was inside a conditional block - removed
2. ❌ Platform-specific links were not wrapped in conditionals - fixed
3. ❌ Blank line between heading and list - removed
4. ❌ Hardcoded context in ID - changed to use {context} variable

Applied new rule:
Links that appear inside conditional blocks in main content must also be inside the same conditional blocks in Additional resources. This ensures platform-specific content (OCP vs ROSA vs OSD) is properly scoped.

Result:

• Merged old and new Additional resources sections into one properly formatted section
• Platform-specific links now correctly wrapped in ifndef::openshift-rosa,openshift-dedicated,openshift-rosa-hcp[]
• All formatting follows documentation standards

Ready for review!

[openshift-ci]

@abrennan89: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/validate-portal	c65f9d0	link	true	/test validate-portal

Full PR test history. Your PR dashboard.

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