console.lua: increase the opacity of the default item background

This needs to strike a fine balance between being visible and having
contrast with the text color and not taking attention away from the
selected item. Make it slightly more opaque to differentiate it more
easily.

Fixes #15711.

player/lua/console.lua

@@ -790,7 +790,7 @@ local function render()
             ass:append('{\\blur0\\bord0\\4aH&ff&\\1c&H' ..
                        option_color_to_ass(opts.selected_back_color) .. '&}')
             if first_match_to_print - 1 + i ~= selected_match then
-                ass:append('{\\1aH&dd&}')
+                ass:append('{\\1aH&cc&}')
             end
             ass:draw_start()
             ass:rect_cw(-opts.padding, 0, max_item_width + opts.padding, line_height)