Email Reminder Job - Update to use new models module

After https://github.com/bcgov/entity/issues/23124 is done, the new models module can now be used with all BE components. The idea is we want to reference the new models module now instead of the models in Legal API.

Need to handle:
- [ ] update requirements.txt to reference models module
- [ ] update code references to refer to new models module
- [ ] any other required updates
- [ ] fix unit tests

Start with requirements.txt, then locate code references to the Legal API models and review the affected unit tests. Update the dependency and references to use the new models module, make any required related updates, and confirm the unit tests pass.

Written by the indexing model from the issue text.