GtkListBox: Remove the warning for set_filter_func when there is a model
In GTK 3 using set_filter_func on a list box with a binded model would result on the filter being ignored and a warning would be displayed, this is expected as one should apply the filter in the model instead.
In GTK 4 filters set in the list box do work an elements are correctly filtered, but still generate an error
Gtk-WARNING **: 21:32:05.214: GtkListBox with a model will ignore sort and filter functions
Aditionally the documentation states
Note that using a filter function is incompatible with using a model (see gtk_list_box_bind_model()).
which is not the case either. In Icon Library, where we draw a few hundred symbolic icons using set_filter_func versus filtering the list model is the difference between search being usable and unusable, due to the slowness of drawing all icons again, so there is a case for allowing both methods.
This problem also applies to GtkFlowBox.