[clang] Remove std::move in GenerateModuleAction::CreateMultiplexConsumer (NFC)

llvm-project/clang/lib/Frontend/FrontendActions.cpp:213:10:
error: moving a local object in a return statement prevents copy elision [-Werror,-Wpessimizing-move]
  213 |   return std::move(Consumers);
      |          ^
/Users/jiefu/llvm-project/clang/lib/Frontend/FrontendActions.cpp:213:10: note: remove std::move call here
  213 |   return std::move(Consumers);
      |          ^~~~~~~~~~         ~
1 error generated.