can not change mount point of dags when enabling git sync from/dags/repo

### Under which category would you file this issue?

Helm chart

### Apache Airflow version

3.1.7

### What happened and how to reproduce it?

when installing airflow using Helm cannot change $AIRFLOW_HOME/dags/repo/YOURGIT dags and its defined in _helpers.yaml.should we can change this

### What you think should happen instead?

can change this from values.yaml

### Operating System

running on k8s

### Deployment

Official Apache Airflow Helm Chart

### Apache Airflow Provider(s)

_No response_

### Versions of Apache Airflow Providers

3.1.7

### Official Helm Chart version

1.19.0

### Kubernetes Version

1.35

### Helm Chart configuration

dags:
gitSync:
branch: dev
containerName: git-sync
credentialsSecret: airflow-git-credentials
enabled: true
period: 30s
ref: HEAD
repo: https://git.com/repo
resources:
limits:
cpu: 200m
memory: 256Mi
requests:
cpu: 100m
memory: 128Mi
rev: HEAD
securityContexts:
container: {}
subPath: ""
uid: 65533

### Docker Image customizations

_No response_

### Anything else?

_No response_

### Are you willing to submit PR?

- [x] 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)