Issue #2495301 by Mile23, mohit_aghera, JeroenT, dcmul, naveenvalecha,...

Issue #2495301 by Mile23, mohit_aghera, JeroenT, dcmul, naveenvalecha, borisson_, cilefen, alivadniy, andypost, xjm: Deprecate user_format_name() and the label_callback for 9.x (not 8.x)