[Turbolev] Enable fuzzing of experimental features

Decreased chance for turning on stable version of Turbolev from 50% to
40%. The experimental flag is enabled in 20% of other cases (so with a
chance of 12%).

Change-Id: I15b9df4e6fd65581593a5150cdd2b95b3c2bf676
Reviewed-on: https://chrome-internal-review.googlesource.com/c/v8/fuzzilli/+/8568096
Commit-Queue: Dominik Klemba <tacet@google.com>
Reviewed-by: Matthias Liedtke <mliedtke@google.com>
Reviewed-by: Victor Gomes <victorgomes@google.com>
Auto-Submit: Dominik Klemba <tacet@google.com>

Author: Dominik Klemba

Sources/FuzzilliCli/Profiles/V8Profile.swift

@@ -716,8 +716,10 @@ let v8Profile = Profile(
             args.append("--turboshaft-typed-optimizations")
         }
 
-        if probability(0.5) {
+        if probability(0.4) {
             args.append("--turbolev")
+        } else if probability(0.15) {
+            args.append("--turbolev-future")
         }
 
         if probability(0.1) {