LibJS: Remove FLATTEN attribute from Interpreter::run_bytecode

This is what caused stack usage to increase so much with the new BC.
Revert it for now so we can restore our old stack limit.

Userland/Libraries/LibJS/Bytecode/Interpreter.cpp

@@ -273,7 +273,7 @@ ThrowCompletionOr<Value> Interpreter::run(SourceTextModule& module)
     return js_undefined();
 }
 
-FLATTEN void Interpreter::run_bytecode()
+void Interpreter::run_bytecode()
 {
     auto* locals = vm().running_execution_context().locals.data();
     auto& accumulator = this->accumulator();