setup_configs should respect deprecation of _LIBCPP_ENABLE_ASSERTIONS

_LIBCPP_ENABLE_ASSERTIONS is deprecated in favor of hardening modes.
In my local setup I had to manually change
```
build:fuzztest-common --copt=-D_LIBCPP_ENABLE_ASSERTIONS=1
```
to
```
build:fuzztest-common --copt=-D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE`
```

For my clang to not emit a compilation error.

I hope there is a way to automatically generate this with https://github.com/google/fuzztest/blob/main/bazel/setup_configs.sh so that I don't have to manually modify the generated file.