Remove obsolete experiment from skpbench.

adlai@ landed http://review.skia.org/398217 as an experiment on
a single perf bot. This affected some perf results. The experiment
is no longer adding value, and obscures our perf data, so let's
roll it back.

Bug: b/40042987
Bug: b/40042242
Change-Id: I165c8775747b818da9df7e4125f85f258eb4790f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/765616
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
4 files changed