Previously, BeanInstanceSupplier had three variants of the
`withGenerator` callback, one with a bi function, one with a function,
and with a supplier. This could lead to compilation failure when the
target type has a method with the same name and a number of arguments
that match another variant.
It turns out the supplier-based variant is only used a shortcut. This
commit deprecates it and update ghe code generation to use the function
instead.
Closes gh-29278