LibJS: Set default bytecode optimization level to Optimize

Author: https://github.com/Hendiadyoin1
Commit: 4a06e68ecd
Pull-request: https://github.com/SerenityOS/serenity/pull/15857
Issue: https://github.com/SerenityOS/serenity/issues/15753
Reviewed-by: https://github.com/alimpfard

Userland/Libraries/LibJS/Bytecode/Interpreter.h

@@ -71,7 +71,7 @@ public:
         None,
         Optimize,
         __Count,
-        Default = None,
+        Default = Optimize,
     };
     static Bytecode::PassManager& optimization_pipeline(OptimizationLevel = OptimizationLevel::Default);