Simplify test spec structure

tests/modules/net_vpc/tftest.yaml

@@ -13,48 +13,16 @@
 # limitations under the License.
 
 module: modules/net-vpc
+common_tfvars:
+  - common.tfvars
 
 tests:
   simple:
-    tfvars:
-      - common.tfvars
-
   subnets:
-    tfvars:
-      - common.tfvars
-      - subnets.tfvars
-
   peering:
-    tfvars:
-      - common.tfvars
-      - peering.tfvars
-
   shared_vpc:
-    tfvars:
-      - common.tfvars
-      - shared_vpc.tfvars
-
   factory:
-    tfvars:
-      - common.tfvars
-      - factory.tfvars
-
   psa_simple:
-    tfvars:
-      - common.tfvars
-      - psa_simple.tfvars
-
   psa_routes_export:
-    tfvars:
-      - common.tfvars
-      - psa_routes_export.tfvars
-
   psa_routes_import:
-    tfvars:
-      - common.tfvars
-      - psa_routes_import.tfvars
-
   psa_routes_import_export:
-    tfvars:
-      - common.tfvars
-      - psa_routes_import_export.tfvars