Use common get_instance function in v2 consoles extension

This patch use common get_instance function in v2 consoles extension.
That can make the instance behavior consistent with v2.1 api. Then
v2.1 and v2 can share same unittest.

Change-Id: Idf501be21178c3c97b1693e48d3fd13b97525299
Merge "Use common get_instance function in v2 consoles extension"