Delete dead trim code

This code was used in tests as part of b/135148702
back in 2019.
Unfortunately we never moved forward with this idea.

I looked in code search and field traces.
All evidence suggests that this code doesn't run today.

Bug: 135148702
Change-Id: I85a9ce668dee472ced62b619e3a61afe1c3928d5
Flag: EXEMPT deleted dead code