Ensure that AAD Pod Identity integration in ASOv2 works well

[matthchr]

Describe the current behavior
ASOv1 has an AAD Pod Identity binding named aso_manager_binding.

Describe the improvement
aso_manager_binding is a fine name when using AAD Pod Identity through its Helm installation, but when using it through the AKS addon, the name of the binding is by default the value used in the selector, which is aso_manager_binding, but since _'s are not allowed in Kubernetes resource names, that causes issues.

We should instead use a selector for ASO v2 that doesn't contain underscores (aso-manager-binding) or something.