Improve vendor release range notes

[DRSDavidSoft]

Summary

• Keep the vendor update table as four columns: Name, Old Version, New Version, and Build Status.
• Move build shields into the fourth column and make them target the explicit release tag, not the vendor repo default branch.
• Restore the Release notes for updated vendors heading above the per-vendor collapsibles.
• Simplify each collapsible summary to just the vendor name.
• Fetch GitHub release notes across the old→new release range when releases are available, with per-release truncation and an overall cutoff.
• Keep the top Release notes · Compare changes links, and avoid the misleading bottom commit-diff-as-release-notes link.

Validation

• git diff --check
• Executed the PR-body generation logic locally against the ⬆️ Update 4 vendored dependencies #3093 version set and verified:
  • four-column table
  • four tag-specific build shields
  • no release-version shields
  • no badge inside the New Version cell
  • restored release-notes section heading
  • vendor-only collapsible summaries
  • Git for Windows includes multiple release-note entries in the range
  • no bottom View full changes between... commit-diff link