NoBackwardTimeZones fails on macOS 26 Preview 3

`System.Tests.TimeZoneInfoTests.NoBackwardTimeZones` fails on macOS 26 preview 3

```plain
Assert.Equal() Failure: Values differ
Expected: 419
Actual:   418
  Stack Trace:
  /Users/vcsjones/Projects/runtime/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/TimeZoneInfoTests.cs(2749,0): at System.Tests.TimeZoneInfoTests.NoBackwardTimeZones()
```