Slack integration via Organization Integrations goes into an infinite loop

### How are you running Flagsmith

- [ ] Self Hosted with Docker
- [ ] Self Hosted with Kubernetes
- [x] SaaS at flagsmith.com
- [ ] Some other way (add details in description below)

### Describe the bug

The Slack integration via "Project>Integrations>Slack" works fine, but when you go to "Organization>Organization Integrations>Slack" it goes into an infinite loop of asking you to pick a project and environment and redirecting back to Slack to authorize.

### Steps To Reproduce

1. Go to Organisation Settings > Organisation Integrations.
2. Under "Project-level integrations", find Slack and click Add integration.
3. Select a project, then select an environment.
4. Click the button to authorize, and complete the Slack authorization flow.
5. You are redirected back to the Organization Integrations page and the Slack modal reopens prompting you to pick a project and environment again.
6. Once you pick project and environment again you are redirected to Slack and back to the same page in Flagsmith again infinitely

### Expected behavior

Once you approve Slack authorisation you should be redirected to pick a Slack channel, not project and environment again.

### Screenshots

_No response_