Deprecate `AggregateUDFImpl::is_nullable` in favour of `return_field`

### Is your feature request related to a problem or challenge?

Deprecate `is_nullable` as the same information is already encoded by the field from `return_field`

https://github.com/apache/datafusion/blob/5f2272219fc0d2f3bbbc4ee54062b41d7f5ab68a/datafusion/expr/src/udaf.rs#L508-L537

### Describe the solution you'd like

Similar to how we did for scalar UDFs: https://github.com/apache/datafusion/pull/17074

### Describe alternatives you've considered

_No response_

### Additional context

_No response_