test/orfs: drop ram_8x7

The ram_8x7 sweep was a one-off case study (good.v vs bad.v
contrasting yosys synth quality). It is not consumed by any other
target — no .bzl, BUILD, or doc outside the directory references it.
Removing it shaves ~3000 lines off the test tree without touching
anything else.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

Author: oharboe