Work around NPC aborting activity due to unbuilt light map

Light map is only built on the player character's z level even with 3D FOV on, and building the light map on all NPCs' levels might be too expensive, so simply let NPCs finish their business when not on the player character's z-level for now, like what was done for non-3D-FOV mode.

src/character.cpp

@@ -2830,8 +2830,7 @@ float Character::fine_detail_vision_mod( const tripoint &p ) const
     tripoint const check_p = p == tripoint_min ? pos() : p;
     tripoint const avatar_p = get_avatar().pos();
     // Light might not have been calculated on the NPC's z-level
-    if( is_avatar() || check_p.z == avatar_p.z ||
-        std::abs( avatar_p.z - check_p.z ) <= fov_3d_z_range ) {
+    if( is_avatar() || check_p.z == avatar_p.z ) {
         ambient_light = std::max( 1.0f,
                                   LIGHT_AMBIENT_LIT - get_map().ambient_light_at( check_p ) + 1.0f );
     } else {