Some pixels of the overlay on filled maps are not being colored

Some pixels of the marking overlay on filled map items are not being colored. This is because the affected pixels within the overlay texture, filled_map_markings.png, are black instead of white.

The issue is most noticeable on filled maps with a light-colored marking, but regular maps (default, mansion, monument, chambers) are affected as well, as their markings are also being colored.

How to reproduce:

Observe any filled map. The issue will be most apparent on light-colored ones, such as the one that can be obtained using the following command:

/give @s minecraft:filled_map[minecraft:map_color=14602026]

Further notes:

The issue arose in snapshot 16w39a when the marking texture was isolated from its base texture and its colorability was introduced. While not directly related to MC-241898, it may be beneficial to address both issues at the same time, as they involve the same texture.