From the roles available with DevTest, which one, that is not the Super User, will give an user the access to the create virtual service and API test in the Portal ?

All supported releases.

The standard role that is not Super User, but allows a user to create a Virtual Service and API test in the Portal is the SV Power.
Add SV Power to the user in question.
The user will need to logout and login back in the Portal to see the changes.

For more information regarding the Standard Permissions with DevTest, please refer to the link below:
Access Control - Standard Permissions: https://docops.ca.com/devtest-solutions/10-4/en/administering/security/access-control-acl/standard-permissions#StandardPermissions-VirtualServicesAdministrationPermission