The default value "false" of "CLEAN_BLOB_UPLOAD_FOLDER" doesn't make sense

Description of problem:

From quay 3.6.2,  quay added a new configuration CLEAN_BLOB_UPLOAD_FOLDER to  reduce S3 storage usage. 

But the default value of CLEAN_BLOB_UPLOAD_FOLDER is always false.

# cat /quay-registry/config.py
.......
    # Automatically clean stale blobs leftover in the uploads storage folder from cancelled uploads
    CLEAN_BLOB_UPLOAD_FOLDER = False

this behavior doesn't make sense from customer point of view. 

If quay doesn't clean up temporary files under `uploads` folder by default, that means it is very possible for customer to pay more money for storage usage.  A lot of  important customers are money-sensitive,  so it doesn't make sense to set CLEAN_BLOB_UPLOAD_FOLDER as false by default.