Ariana Grande and Cynthia Erivo's friendship was reportedly 'holding on by threads' while they worked together on Wicked in the US, Cynthia has said in a new interview published this week, reigniting months of feud rumours surrounding the two stars. During the long Wicked press tour, Ariana and Cynthia were presented as inseparable, with their bond becoming part of the film's marketing almost as much as their performances. After the release of t…