Problem with Rotation of Fernet Key

### Official Helm Chart version

1.15.0 (latest released)

### Apache Airflow version

2.9.3

### Kubernetes Version

1.31.4

### Helm Chart configuration

```yaml
createUserJob:
applyCustomEnv: false
useHelmHooks: false
dags:
gitSync:
branch: main
credentialsSecret: airflow-git-credentials
enabled: true
repo: https://github.com/dacamposol/kg-infra.git
subPath: dags
extraEnv: |
- name: AIRFLOW__API__AUTH_BACKENDS
value: 'airflow.api.auth.backend.basic_auth'
migrateDatabaseJob:
applyCustomEnv: false
jobAnnotations:
'argocd.argoproj.io/hook': Sync
useHelmHooks: false
useStandardNaming: true
```

### Docker Image customizations

_No response_

### What happened

> [!IMPORTANT]
> This is an instance managed via ArgoCD.

1. I created a connection from type HTTP directly from the Web Server UI.
2. I modified a field in the Argo Application in regards of adding the `.extraEnv` to allow REST API calls.
3. I accessed again to the Web Server UI.
4. Cannot open the **Connections** section (all others work fine).

Error in the `webserver` Pod:

```bash
File "/home/airflow/.local/lib/python3.12/site-packages/sqlalchemy/orm/mapper.py", line 3702, in _event_on_load
instrumenting_mapper._reconstructor(state.obj())
File "/home/airflow/.local/lib/python3.12/site-packages/airflow/models/connection.py", line 213, in on_db_load
if self.password:
^^^^^^^^^^^^^
File "/home/airflow/.local/lib/python3.12/site-packages/sqlalchemy/orm/attributes.py", line 606, in __get__
retval = self.descriptor.__get__(instance, owner)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/airflow/.local/lib/python3.12/site-packages/airflow/models/connection.py", line 340, in get_password
return fernet.decrypt(bytes(self._password, "utf-8")).decode()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/airflow/.local/lib/python3.12/site-packages/cryptography/fernet.py", line 211, in decrypt
raise InvalidToken
cryptography.fernet.InvalidToken
```

When I go to my Argo CD deployment, I can indeed see how for the Airflow application, the `airflow-fernet-key` got recreated at the same time than the sync happened.

I am assuming the Secret got recreated and somehow the rotation process failed, so the **Connections** are now encrypted with the old key, and thus cannot be accessed anymore.

### What you think should happen instead

_No response_

### How to reproduce

1. Have an Airflow Cluster managed by Argo CD.
2. Create a connection in that cluster.
3. Modify settings in the Application, and wait for Sync.
4. Attempt to access again to the Connections in the aforementioned cluster.

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start with airflow/models/connection.py and the webserver traceback to trace how Fernet decrypts stored connection passwords. Reproduce the ArgoCD sync using the listed Helm configuration and inspect the airflow-fernet-key Secret before and after synchronization. Done should define and verify expected connection access when the application configuration changes.

Written by the indexing model from the issue text.