Revert "Earlysquisher: optipng before blockimgdiff"

This reverts commit e26afe1d7c6588ddd6a5e1e8783f133af318f75a.

Change-Id: I6c624f6718cfe978fe4f16b2fe3cb1769de1700b
Merge "Revert "Earlysquisher: optipng before blockimgdiff"" into L5