Bell contains hidden pixels with alpha 0

Relates to MC-245930.

The bug

There are several pixels in textures/entity/bell/bell_body.png which are at an alpha level of 0, but nonetheless have color data.

How to reproduce

If you have ImageMagick, the following command can be used:

convert bell_body.png -alpha off noalphabell.png

Expected results

All pixels not actually used in this texture would be zero-opacity black.

Actual results

There is remaining color data.

How to fix

A fixed version of this texture is attached under bell_body.png. Also attached is the original version affected by this issue, as well as versions of both of these with the alpha channel disabled.