Volume is missing for sshKeySecret when dag persistence is enabled.

### Official Helm Chart version

1.7.0 (latest released)

### Apache Airflow version

2.3.4

### Kubernetes Version

1.22.6

### Helm Chart configuration

```
# Git sync
dags:
persistence:
enabled: true
size: 1Gi
storageClassName:
accessMode: ReadWriteOnce
existingClaim: airflow-dags
subPath: ~
gitSync:
enabled: true
repo: "ssh://git@..."
branch: "main"
rev: HEAD
depth: 1
maxFailures: 0
subPath: ""
sshKeySecret: airflow-ssh-secret
```

### Docker Image customisations

_No response_

### What happened

This commit: https://github.com/apache/airflow/commit/3fc895b9dfe8e7b77538bd80754fb17ccf92db49 causes the following error because volumeMount is created but the volume is missing:
```upgrade.go:369: [debug] warning: Upgrade "airflow" failed: cannot patch "airflow-scheduler" with kind Deployment: Deployment.apps "airflow-scheduler" is invalid: spec.template.spec.containers[2].volumeMounts[0].name: Not found: "dags"```

### What you think should happen instead

I don't see any relation between dag persistency and git-sync configuration. The fact is that the same configuration works when `credentialsSecret` is defined but stopped working with `sshKeySecret`.

### How to reproduce

Follow commit https://github.com/apache/airflow/commit/3fc895b9dfe8e7b77538bd80754fb17ccf92db49

### 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 by reviewing commit 3fc895b9dfe8e7b77538bd80754fb17ccf92db49 and reproducing the Helm upgrade with dag persistence and gitSync.sshKeySecret enabled. Trace the generated Deployment volumeMounts and volumes; done means the chart renders and upgrades successfully without the missing "dags" volume error.

Written by the indexing model from the issue text.