Add tempest api tests for subnet pools RBAC

Change-Id: Ie6e26acd5e9c3acd2ee86a9c354c4a2934aa4bce
Partial-Bug: #1862032
Depends-On: https://review.opendev.org/#/c/710755/
diff --git a/.zuul.yaml b/.zuul.yaml
index 2e99198..2c3c532 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -65,6 +65,7 @@
         - quota_details
         - rbac-policies
         - rbac-security-groups
+        - rbac-subnetpool
         - router
         - router-admin-state-down-before-update
         - router_availability_zone