Update v4 migration docs

[nscuro]

Relates to DependencyTrack/dependency-track#6260

[Copilot]

Pull request overview

Updates the v4→v5 migration documentation to match current v4-migrator output and to better guide operators in interpreting verify / run logs during rehearsal and real migrations.

Changes:

• Refreshes verify example output (Flyway head wording, terminator line, and a new Note column explaining expected row-count deltas).
• Expands run output examples to include phase completion lines and final “Migration completed” confirmation.
• Adds additional explanatory guidance around interpreting row-count reductions and completion signals.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
docs/tutorials/rehearsing-the-v4-migration.md	Updates the rehearsal walkthrough’s expected verify/run output and guidance to match current migrator behavior.
docs/guides/administration/migrating-from-v4.md	Updates the admin migration guide’s verify semantics/output and adds explicit documentation of phase completion / success indicators.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.