Unused pixels in powered lightning rod texture

May relate to: MC-159560

The bug

Most of the pixels in lightning_rod_on, the texture lightning rods use when struck, are unused - only the top 4x4 region and leftmost two columns are actually used by the game. The rest can therefore be safely removed from the texture without affecting it, making it more clear what parts of the texture are actually used.

How to fix

Remove all the unused pixels from the texture file. I've attached a fixed version.