Since wasm optimizations are independent of JS optimizations, we can
just combine the "no_liftoff" variant with the existing "stress"
variant (which has the similar "--always-opt" option for JS), and add
a "Liftoff only" variant as part of "nooptimization".

This gives more coverage to find bugs like https://crrev.com/c/1543354
more easy.

R=mstarzinger@chromium.org, machenbach@chromium.org

Change-Id: I81bb22074c59dcb650a05252da43a4170cd467ac
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559740
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60714}