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)