Review and update feature registrations in azd-hooks/preprovision.{ps1,sh}

[clarenceb]

Not all feature flags are required as some of these previously preview features are now GA.

See files:

• https://github.com/Azure-Samples/aks-store-demo/blob/main/azd-hooks/preprovision.sh
• https://github.com/Azure-Samples/aks-store-demo/blob/main/azd-hooks/preprovision.ps1

GAs:

• KEDA (don't require AKS-KedaPreview feature flag)
• Prometheus (don't require AKS-PrometheusAddonPreview feature flag)

The other features still appear to be in public preview.

[pauldotyu]

Thanks for raising this @clarenceb!