Removes files from docker-context-files if not used (#13830)
Removes files from docker-context-files if not used (#13830)

In case docker-context files are not used during build, they
shoudl be cleaned just before the build to make sure that
docker context does not contain extra files here. Otherwise
files left from previous runs might be in the context and cause
cache invalidation if you are building the images locally.
lyft/incubator-airflow,nathanielvarona/airflow,apache/incubator-airflow,sekikn/incubator-airflow,cfei18/incubator-airflow,bolkedebruin/airflow,danielvdende/incubator-airflow,Acehaidrey/incubator-airflow,mistercrunch/airflow,sekikn/incubator-airflow,apache/airflow,dhuang/incubator-airflow,cfei18/incubator-airflow,mistercrunch/airflow,nathanielvarona/airflow,dhuang/incubator-airflow,cfei18/incubator-airflow,apache/airflow,apache/airflow,cfei18/incubator-airflow,lyft/incubator-airflow,lyft/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,bolkedebruin/airflow,Acehaidrey/incubator-airflow,mistercrunch/airflow,cfei18/incubator-airflow,dhuang/incubator-airflow,danielvdende/incubator-airflow,nathanielvarona/airflow,mistercrunch/airflow,Acehaidrey/incubator-airflow,dhuang/incubator-airflow,sekikn/incubator-airflow,apache/incubator-airflow,danielvdende/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,bolkedebruin/airflow,Acehaidrey/incubator-airflow,apache/incubator-airflow,danielvdende/incubator-airflow,sekikn/incubator-airflow,apache/incubator-airflow,lyft/incubator-airflow,danielvdende/incubator-airflow,bolkedebruin/airflow,nathanielvarona/airflow,apache/airflow,bolkedebruin/airflow,apache/airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow