Change k8s default version to 1.8.9 (#2360)
Change k8s default version to 1.8.9 (#2360)

* change to k8s 1.8.9

rjtsdl/acs-engine,jackfrancis/acs-engine,rjtsdl/acs-engine,rjtsdl/acs-engine,Azure/acs-engine,rjtsdl/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,rjtsdl/acs-engine