Incorrect local time zone reported on macOS

[filipnavara]

Steps to repro:

• Set macOS time zone to "Phoenix, AZ" / "Mountain Standard Time"
  
• Verify that local time points to the correct time zone:

> ls -l /etc/localtime 
lrwxr-xr-x  1 root  wheel  41 Jun  8 00:12 /etc/localtime -> /var/db/timezone/zoneinfo/America/Phoenix

• Print TimeZoneInfo.Local.Id in .NET code

Actual result:

• TimeZoneInfo.Local.Id reports America/Creston

Expected result:

• TimeZoneInfo.Local.Id reports America/Phoenix

Notes:

• America/Creston is a deprecated alias in TZ DB data

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-datetime
See info in area-owners.md if you want to be subscribed.

[filipnavara]

This is breaking interoperability of our product. We use the system time zones to create iCalendar data that are then sent to various 3rd-party servers. Some of those servers cannot handle the legacy time zone names correctly.