message: Use a single node when doing outlining
diff: @@ -136,7 +136,7 @@ Status PoplarCompiler::RunHloOptimization(HloModule* hlo_module,
  HloDumper dump_hlo) {
  HloPassPipeline pipeline("IPU", dump_hlo);
  pipeline.AddPass<Inliner>();
  - pipeline.AddPass<Outliner>(2);
  + pipeline.AddPass<Outliner>(1);
  pipeline.AddPass<FuseOps>();
  pipeline.AddPass<HloSubcomputationUnification>();
  pipeline.AddPass<HloCSE>(false);
  