Audit log generates "segment created" event when editing an existing segment

### How are you running Flagsmith

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

### Describe the bug

When editing an existing segment (e.g. adding or removing a trait rule), the audit log records an incorrect "New segment created" event in addition to the expected "Segment updated" event.

Editing a segment should only produce a modification/update event.

### Steps To Reproduce

1. Create a segment
2. Edit the segment (e.g. add a trait condition)
3. Save the segment
4. Check the audit log

### Expected behavior

A single "Segment updated" event appears in the audit log.

### Screenshots

Two events appear:
1. "New segment with the same name created" (incorrect)
2. "Segment updated"