Resolve ja-JP-mac locale exceptions
The patch from !401 (merged) included an exception for the ja-JP-mac locale to address #41372 (closed).
We opened a mozilla bug for that specific issue https://bugzilla.mozilla.org/show_bug.cgi?id=1796161 If that is resolved, we would no longer require the ja-JP-mac exception added in the above patch.
There is also a more generic mozilla bug to remove the ja-JP-mac distinction entirely by renaming the packaged locale to ja-JP-macos https://bugzilla.mozilla.org/show_bug.cgi?id=1726586 If that is resolved, then we similarly won't need our exception, but there may also be other places where we can remove ja-JP-mac exceptions.