Fix protocol endorsement test

[gterzian]

FIX https://github.com/massalabs/massa/issues/3433

• [ ] document all added functions
• [ ] try in sandbox /simulation/labnet
• [ ] unit tests on the added/changed features
  • [ ] make tests compile
  • [ ] make tests pass
• [ ] add logs allowing easy debugging in case the changes caused problems
• [ ] if the API has changed, update the API specification