GNU test CI needs some more locale work

I fixed some issues in https://github.com/uutils/coreutils/pull/2753 for the tr PR ( https://github.com/uutils/coreutils/pull/2502 )

but we still have this one

`./tests/misc/sort-float.sh: line 58: warning: setlocale: LC_ALL: cannot change locale (none): No such file or directory`

Core: https://github.com/coreutils/coreutils/blob/master/tests/misc/sort-float.sh#L58