associate SubnetPoolsTestJSON with default-subnetpools extension

Change-Id: Id89c0971de4537c666a5612352b1f2ef2ded9d65
Related-prod: PRODX-4874
(cherry picked from commit cf46b50b870456f6749d034741711e4b98a342b8)
(cherry picked from commit a1a4c375bec72d888c4be04b6006914a828c1ad3)
(cherry picked from commit d10d3ea7f40e5e9a06a0109d93aaaad5540587bf)
(cherry picked from commit bad84ba706ad86f9e22e3b13fd64f587f2fdb56c)
1 file changed