Remove or reduce level of 'Either all or no Ingress should have the priority specified' error message

[lewis-jackson-bots]

Is your feature request related to a problem? Please describe.

We're seeing this error message in our logs: https://github.com/Azure/application-gateway-kubernetes-ingress/blob/dd55e83b42305c549ca20125fd51728994610956/pkg/appgw/requestroutingrules.go#L500

But as far as I can tell, this error is ignorable as the code is perfectly capable of handling the assignment of nil priorities to sequential numbers while leaving set priorities alone.

Describe the solution you'd like This could be a warning or info level log event.