fix some issues with locale (replace "LANGUAGE" with "LC_ALL")

[jhscheer]

My understanding is that, as long as uutils does not support locales, we try to stick to the C locale.

However, a conversation #2361 (comment) with @tertsdiepraam made me aware that LANGUAGE=C is not enough and that LC_ALL=C is needed as the environment variable that overrides all the other localization settings.

e.g.

$ LANGUAGE=C id foobar
id: ‘foobar’: no such user

$ LC_ALL=C id foobar
id: 'foobar': no such user

This PR does:

• replace LANGUAGE with LC_ALL as environment variable in the tests
• fix the the date string of affected uutils
• replace ‘ and ’ with '

[sylvestre]

Seems that this change is failing on mac:

run: /Users/runner/work/coreutils/coreutils/target/debug/coreutils who -u
current_directory_resolved: 
run: gwho -u
actual: "runner   console      Jun 23 06:37 00:34         196\n"
expect: "runner   console      Jun 23 06:37  old          196\n"
---- test_who::test_users stderr ----
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `["runner", "console", "Jun", "23", "00:34", "196"]`,
 right: `["runner", "console", "Jun", "23", "old", "196"]`', /Users/runner/work/coreutils/coreutils/tests/by-util/test_who.rs:170:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    test_who::test_users