target_x and trial_chambers map icons are misaligned from each other by one pixel, despite being identical in shape

Discovered while testing MC-269729.

The bug

The map icons minecraft:target_x and minecraft:trial_chambers both have the same outer shape (a 7x7 square with one pixel taken out of the centers of each of the four edges). However, one is shifted a pixel to the side of the other, resulting in misalignment.

How to reproduce

1. Create a new superflat world
2. Obtain an empty map, and use it
3. Run this command:

   /give @s minecraft:filled_map[minecraft:map_id=0,minecraft:map_decorations={1:{type:"minecraft:target_x",x:20,z:20,rotation:0},2:{type:"minecraft:trial_chambers",x:20,z:20,rotation:0}}]

4. Look at the map, specifically the decoration icon

Expected results

Since there is a target_x and trial_chambers icon at exactly the same position, and they have the exact same shape, you'd just see a trial_chambers icon.

Actual results

The outline of the target_x is visible, causing the outline of the icon to appear strangely thicker on the right.

How to fix

The resource pack attached fixes this issue entirely: it makes map icons 16x16 and shifts both of these icons along by a pixel so they're correctly aligned with each other, eliminating this issue (refer to screenshots). It fixes this for other map icons as well - see MC-269729.