[hail] use rename in dndarray (#9358)
[hail] use rename in dndarray (#9358)

When I first dndarray, I did not know you could use rename for keys. This
change takes advantage of rename instead of using the `r_field` and `c_field`
indirection.
cseed/hail,cseed/hail,hail-is/hail,cseed/hail,cseed/hail,danking/hail,hail-is/hail,danking/hail,cseed/hail,danking/hail,cseed/hail,danking/hail,danking/hail,hail-is/hail,hail-is/hail,hail-is/hail,cseed/hail,danking/hail,hail-is/hail,danking/hail,danking/hail,hail-is/hail,hail-is/hail,cseed/hail