skip subnetpools tests if default-subnetpools extension not defined

Some subnetpool tests don't have association with certain extension.
This doesn't allow to disable those tests via enabled extensions

Related-prod: PRODX-3721
Change-Id: Ic60654caca3f4fa4473b5cf75872b3131506da11
(cherry picked from commit 91215cac0c54ca7012edaec0c1c6689e041ccd60)
3 files changed