ENYO-3521: fix an undesired apparition of the button "cancel" on the wait Pop-up during the 1st phase of PGB action.

Link to the JIRA ticket: https://enyojs.atlassian.net/browse/ENYO-3521

Ready for review.

Tested on Chrome(Windows 7)
Enyo-DCO-1.1-Signed-off-by: Rafik Adiche mahmoud-rafik.adiche@hp.com