Fix Helm GitSync dag volume mount from pod-template-file (#15331)
Fix Helm GitSync dag volume mount from pod-template-file (#15331)

This fixes an issue where the workers cannot find the dag that is meant to run.

With git-sync enabled, the airflow_dag location is being set to where the dags are being cloned to, ex `$AIRFLOWHOME/dags/repo/dags`, but the subpath is remapping it to `$AIRFLOWHOME/dags`, thus the workers are not able to find the actually dag. 

Also related: https://github.com/apache/airflow/blob/master/chart/templates/_helpers.yaml#L333

Removing the subpath resolves this issue. I locally ran the helm unit tests, and it succeeded.
Acehaidrey/incubator-airflow,mistercrunch/airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,dhuang/incubator-airflow,nathanielvarona/airflow,sekikn/incubator-airflow,bolkedebruin/airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,danielvdende/incubator-airflow,apache/incubator-airflow,cfei18/incubator-airflow,sekikn/incubator-airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,dhuang/incubator-airflow,cfei18/incubator-airflow,bolkedebruin/airflow,apache/airflow,danielvdende/incubator-airflow,cfei18/incubator-airflow,lyft/incubator-airflow,bolkedebruin/airflow,apache/airflow,apache/incubator-airflow,nathanielvarona/airflow,nathanielvarona/airflow,nathanielvarona/airflow,bolkedebruin/airflow,apache/incubator-airflow,lyft/incubator-airflow,bolkedebruin/airflow,mistercrunch/airflow,lyft/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,apache/airflow,lyft/incubator-airflow,apache/incubator-airflow,sekikn/incubator-airflow,apache/airflow,cfei18/incubator-airflow,mistercrunch/airflow,apache/airflow,sekikn/incubator-airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,mistercrunch/airflow,dhuang/incubator-airflow,danielvdende/incubator-airflow,dhuang/incubator-airflow