What is the workflow of an editor in this case?
You can't know. Having been an editor for the past decade, I'm pretty sure I've done all of the following three options:


I disagreed with the reviewer who said that there is nothing new in the paper and ignored that person in the second round of reviews.
I agreed with the reviewer who said that there is nothing new in the paper, felt that the comments by the other reviewer had been addressed, and didn't send the paper to that other reviewer again because it would just be a waste of their time.
I couldn't figure out who is right and sent it to a third reviewer to get a tie breaker and a second (actually third) opinion.


Point being: There's no way you can know. Have patience with the process and see what happens.