Platform 25.0 PiT issues

[manolo]

Blockers

• [PiT V25] TestEngine with ID 'junit-jupiter' failed to discover tests testbench-demo#185
• [PiT V25]addon is not working with Vaadin 25 form-filler-addon#154
  • should remove this starter from V25 PiT list, we are dropping this support.
  • PiT 25.0: tasks to do with form-filler removal in 25.0 form-filler-addon#155
• https://github.com/vaadin/start/issues/3407
• PiT 24.9: Cannot run app in prod mode local. No instructions walking-skeleton#110
  • same issue with PiT 24.9
•  PiT 25.0: layouts denied by default should be covered by migration flow#21956
• Feature flag for component styles doesn't work in Gradle projects flow#22073

Non blockers