ADB controller: Update autonomous database provisioning sample yaml using ECPU

The current example for ADB serverless provisioning is not working in my OCI tenancy because it is using OCPUs by default.
Sample should use the ECPU model available in any tenancy:

...
    dbWorkload: OLTP
    computeModel: ECPU
    computeCount: 4
    licenseModel: BRING_YOUR_OWN_LICENSE
...