Cushion placement subtitles are now directly inconsistent with paintings/item frames

When you place a cushion, the subtitle is “Cushion placed”.

As of 26.4 snapshot 2, this directly conflicts with the changed subtitles for block, item frame and painting placement, which now use “[thing] is placed”. Cushions erroneously emit the “is “.

To fix, change this caption to “Cushion is placed”.