docs: remove embedded PostgreSQL backup instructions from upgrade guide

[d-bytebase]

Summary

• Removed the embedded PostgreSQL backup and restore section from the upgrade documentation
• Updated section heading to clarify that backup instructions are for external PostgreSQL only
• Simplified the documentation structure by removing the no-longer-recommended embedded option

Test plan

• Review documentation changes for accuracy
• Verify all external PostgreSQL instructions remain intact
• Confirm section structure and formatting are correct

🤖 Generated with Claude Code

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Project	Deployment	Preview	Comments	Updated (UTC)
bytebase-com	✅ Ready	Preview	💬 Add feedback	Aug 12, 2025 0:38am

[Copilot]

Pull Request Overview

This PR removes the embedded PostgreSQL backup instructions from the Bytebase upgrade documentation, focusing exclusively on external PostgreSQL setup which is the recommended approach. The change simplifies the documentation by eliminating the no-longer-recommended embedded option.

• Removed the entire "Embedded PostgreSQL" section with backup and restore instructions
• Updated the main section heading to specify "External PostgreSQL" only
• Restructured headings to eliminate the now-unnecessary "External PostgreSQL (Recommended)" subsection

[github-actions]

📝 Broken Links Check Report

Note: Entries under /api-reference/ are likely false positives and can be ignored.

The following is the output from the broken links check:

found 16 broken links in 9 files

integrations/api/audit-log.mdx
 ⎿  /api-reference/auditlogservice/post-v1auditlogs:search

integrations/api/authentication.mdx
 ⎿  /api-reference/authservice/post-v1authlogin

integrations/api/data-classification.mdx
 ⎿  /api-reference/settingservice/patch-v1settings
 ⎿  /api-reference/databaseservice/patch-v1instances-databases

integrations/api/issue.mdx
 ⎿  /api-reference/issueservice/post-v1projects-issues

integrations/api/permission.mdx
 ⎿  /api-reference/workspaceservice/get-v1workspaces-:getIamPolicy
 ⎿  /api-reference/projectservice/get-v1projects-:getIamPolicy
 ⎿  /api-reference/roleservice/get-v1roles
 ⎿  /api-reference/userservice/get-v1users
 ⎿  /api-reference/groupservice/get-v1groups

integrations/api/plan.mdx
 ⎿  /api-reference/planservice/post-v1projects-plans
 ⎿  /api-reference/sheetservice/post-v1projects-sheets

integrations/api/release.mdx
 ⎿  /api-reference/releaseservice/post-v1projects-releases

integrations/api/rollout.mdx
 ⎿  /api-reference/rolloutservice/post-v1projects-rollouts

integrations/api/sql-review.mdx
 ⎿  /api-reference/releaseservice/post-v1projects-releases:check
 ⎿  /api-reference/sqlservice/post-v1sqlcheck