message: set the experimentation to preferred CONTROL for the outliner
diff: @@ -2275,7 +2275,7 @@ bool outline_candidate(
  if (experiments_contexts->count(method) == 0) {
  auto exp = ab_test::ABExperimentContext::create(
  &cfg, method, "outliner_v1",
  - ab_test::ABExperimentPreferredMode::PREFER_TEST);
  + ab_test::ABExperimentPreferredMode::PREFER_CONTROL);
  experiments_contexts->insert({method, std::move(exp)});
  }
  TRACE(ISO, 7, "[invoke sequence outliner] before outlined %s from %s\n%s",
  