[editdataset]existing certified info is erased when user add/edit a new certify field

[junlincc]

i have existing certified metrics with both CERTIFIED BY and CERTIFICATION DETAILS filled. if i add or edit another certified metrics, or any, all the existing certified metrics info is erased.
in below video, when i revisit the existing certified metrics after adding a second/edit another certified field, i see blank fields of CERTIFIED BY and CERTIFICATION DETAILS.
https://user-images.githubusercontent.com/67837651/130172784-15be5621-5b95-4fd9-9a75-0ce6b84c7558.mov

expected behavior: existing fields should not be erased when new ones are added or edited.

@geido @pkdotson 🙏