Don't include plating thickness when drawing hole clearance lines.

We don't include it in the router, and the code didn't
differentiate between plated and non-plated holes, and it confuses
users.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/15575

pcbnew/pcb_painter.cpp

@@ -1670,8 +1670,6 @@ void PCB_PAINTER::draw( const PAD* aPad, int aLayer )
             }
             else if( aPad->GetEffectiveHoleShape() && clearance > 0 )
             {
-                clearance += m_holePlatingThickness;
-
                 std::shared_ptr<SHAPE_SEGMENT> slot = aPad->GetEffectiveHoleShape();
                 m_gal->DrawSegment( slot->GetSeg().A, slot->GetSeg().B,
                                     slot->GetWidth() + 2 * clearance );