"No changes found" shown in already-applied change requests

### 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

When viewing a change request or scheduled change, we show a diff of the changes that will be applied:

However, after the change request is applied, we show a banner with "No Changes Found":

This is misleading as it gives the impression that this change request contains no changes, which should be impossible.

### Steps To Reproduce

1. Schedule a feature to be enabled
2. Publish the change
3. View the scheduled change again

### Expected behavior

A scheduled change's diff should be relative to the state of features at the time the change was created, not to the current state of the feature.

I don't know if this information is stored to begin with, which might be tricky. If that's not possible, we should remove the "No changes found" message altogether.

### Screenshots

_No response_