Recreating an environment with the same key

**Describe the bug**
I don't know if it is a feature or a bug since I guess environment key should be generated randomly.
When deleting an environment, and then creating a new one with the same environment key. I get the following error
`duplicate key value violates unique constraint "environments_environment_api_key_key"`

**To Reproduce**

Steps to reproduce the behavior:

1. Create an environment with an

```
curl --request POST \
--url https://flagsmith-api.mybrand.com/api/v1/environments/\
--header 'Authorization: Token myToken' \
--header 'Content-Type: application/json' \
--data '{
"name": "myEnv",
"api_key": "deadBeef",
"project": "1"
}'
```

2. Delete it (via API, or UI)
3. Create a new environment with the previous command

**Expected behavior**
After running the 3 commands, the environment is available.
I think this can be achievable with different options:
- A new env is created (but the unique constraint on the env key has to be changed...)
- The env is restored (via the soft delete record)

**How are you running Flagsmith?**

- [ ] Self Hosted with Docker
- [X] Self Hosted with Kubernetes
- [ ] SaaS at flagsmith.com
- [ ] Some other way

**Additional context**
Running version 2.83.0