builder: Cleanup label over-/underline handling
builder: Cleanup label over-/underline handling

There really is no reason to also close over/underline tags when we have
a right margin and a non-black over/underline color.
The git blame for these lines also doesn't give us any insights as to
why it was done this way.

jaagr/polybar,jaagr/polybar,jaagr/polybar