CI: Increase flavor to en1.large - some jobs were failing Tempest jobs

Author: markgoddard

.github/workflows/stackhpc-all-in-one.yml

@@ -38,7 +38,7 @@ on:
       vm_flavor:
         description: Flavor for the all-in-one VM
         type: string
-        default: en1.medium
+        default: en1.large
       vm_network:
         description: Network for the all-in-one VM
         type: string