The JSON payload version of the super user signup route is not used
anywhere significant. This PR removes it.
## Automation
/test sanity authentication
### 🔍 Cypress test results
<!-- This is an auto-generated comment: Cypress test results -->
> [!TIP]
> 🟢🟢🟢 All cypress tests have passed! 🎉🎉🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/11830003644>
> Commit: d051ed852ff68727805a81b5b59b54bdb50f1d2e
> <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=11830003644&attempt=1"
target="_blank">Cypress dashboard</a>.
> Tags: `@tag.Sanity, @tag.Authentication`
> Spec:
> <hr>Thu, 14 Nov 2024 03:53:00 UTC
<!-- end of auto-generated comment: Cypress test results -->
## Communication
Should the DevRel and Marketing teams inform users about this change?
- [ ] Yes
- [x] No
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **New Features**
- Updated user creation process to use URL-encoded data instead of JSON
for super user creation.
- **Bug Fixes**
- Removed deprecated `createSuperUser` methods from the API and server
controllers, streamlining user management.
- **Chores**
- Modified setup scripts to reflect changes in user data transmission
for creating super users.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **Bug Fixes**
- Updated the loop condition in the URL encoding functionality for
improved reliability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
