tests/cp/preserve-gid: Failure to load locales

[drinkcat]

After #8380, tests/cp/preserve-gid still fails (at least locally for me).

Very simplified repro steps:

cargo build -p uu_cp
sudo -u nobody target/debug/cp

fails with

Could not init the localization system: Locales directory not found: Development locales directory not found at .../dev/coreutils/coreutils/src/uucore/../uu/cp/locales or .../dev/coreutils/coreutils/src/uucore/cp

(this assumes that user nobody is not able to read locales -- my home directory has permission 700 which blocks it)

I also tried to use the release build, but that's broken for different reason: #8381.

I've seen similar failures, e.g. on Windows (#8263). I was wondering if we could embed the default localization en-US in the binaries? I think that matches what GNU coreutils does. (@sylvestre for ideas... since you added localization support)

[julian-klode]

This is not particularly unsurprising and in fact, the translation support has a FIXME in it to embed the en-US locale, and some idea how to do that.

[drinkcat]

Fixed by #8423, thanks @sylvestre !