After looking around on the internet and in Visual Studio, I'm declaring the answer as: No.
It isn't possible anymore. if you do find how, please answer the question and I will mark your answer as the correct one.
I also added an item on the Visual Studio User Voice page: http://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/4659318-bring-back-all-build-definitions-in-team-explore