[clang-tools-extra] [clang-tidy] Enable `modernize-return-braced-init-list`'s tests in C++11 (PR #158196)

[Baranov Victor via cfe-commits]

vbvictor wrote:

> > It will be c++11-or-later by default:
> 
> That's sounds very fragile, if the standard is important, the test should be explicit about it.
> 
> Otherwise anyone can bump that standard in run-clang-tidy.py in the future to something else and suddenly this test no longer tests C++11. CI won't catch that.

Maybe then we could fail test if `std` flag isn't passed to `check_clang_tidy.py`?
This will encourage all new developers to set c++ standard explicitly all the time.

https://github.com/llvm/llvm-project/pull/158196