Include Plugins with GitSync

### Official Helm Chart version 1.18.0 (latest released) ### Apache Airflow version 3.1.5 ### Kubernetes Version v1.33.4 ### Helm Chart configuration GitSync syncs DAGs (and other configured paths) but does not sync the `$AIRFLOW_HOME/plugins` directory Plugins placed in the repo are ignored unless they are manually baked into the image or mounted separately. https://airflow.apache.org/docs/apache-airflow/stable/administration-and-deployment/plugins.html ### Docker Image customizations _No response_ ### What happened _No response_ ### What you think should happen instead _No response_ ### How to reproduce Deploy airflow with gitsync enabled, no special configuration. ### 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)