Fix the addons_test to work with xhyve.
Fix the addons_test to work with xhyve.

When you run with the xhyve driver, the addon-manager has a different
name.

endocode/minikube,kubernetes/minikube,dalehamel/minikube,dongsupark/minikube,kubernetes/minikube,dims/minikube,r2d4/minikube,warmchang/minikube,dlorenc/minikube,dongsupark/minikube,warmchang/minikube,abbytiz/minikube,warmchang/minikube,mikegrass/minikube,dims/minikube,cu12/minikube,mikegrass/minikube,skipjaq/minikube,dlorenc/minikube,aaron-prindle/minikube,dlorenc/minikube,dongsupark/minikube,cu12/minikube,dlorenc/minikube,warmchang/minikube,abbytiz/minikube,dalehamel/minikube,mikegrass/minikube,dalehamel/minikube,r2d4/minikube,dlorenc/minikube,warmchang/minikube,dlorenc/minikube,kubernetes/minikube,warmchang/minikube,aaron-prindle/minikube,kubernetes/minikube,r2d4/minikube,kubernetes/minikube,kubernetes/minikube,endocode/minikube,dlorenc/minikube,abbytiz/minikube,warmchang/minikube,cu12/minikube,dims/minikube,endocode/minikube,kubernetes/minikube,skipjaq/minikube,skipjaq/minikube,dlorenc/minikube,aaron-prindle/minikube