make parties_generator create new zkapp accounts

[ghost-not-in-the-shell]

Explain your changes: This PR makes parties_generator would actually generate new accounts instead. Now using zkapp account would not create new accounts.

Explain how you tested your changes: I tested it with the fuzzy zkapp tests.

Checklist:

• [ ] Modified the current draft of release notes with details on what is completed or incomplete within this project
• [ ] Document code purpose, how to use it
  • Mention expected invariants, implicit constraints
• [ ] Tests were added for the new behavior
  • Document test purpose, significance of failures
  • Test names should reflect their purpose
• [ ] All tests pass (CI will check this if you didn't)
• [ ] Serialized types are in stable-versioned modules
• [ ] Does this close issues? List them

• Closes #11245