[tests] Ignore linkall tests that require globalization support.

.NET doesn't have any globalization support yet.

Ref: dotnet#8906

This fixes these tests:

    LinkAll.Calendars.CalendarTest
        [FAIL] Hijri :   Calendar
            Expected string length 34 but was 38. Strings differ at index 21.
            Expected: "System.Globalization.HijriCalendar"
            But was:  "System.Globalization.GregorianCalendar"
            --------------------------------^
                at LinkAll.Calendars.CalendarTest.Hijri() in [...]/xamarin-macios/tests/linker/ios/link all/CalendarTest.cs:line 28

        [FAIL] ThaiBuddhist :   Calendar
            Expected string length 41 but was 38. Strings differ at index 21.
            Expected: "System.Globalization.ThaiBuddhistCalendar"
            But was:  "System.Globalization.GregorianCalendar"
            --------------------------------^
                at LinkAll.Calendars.CalendarTest.ThaiBuddhist() in [...]/xamarin-macios/tests/linker/ios/link all/CalendarTest.cs:line 35

        [FAIL] UmAlQura :   Calendar
            Expected string length 37 but was 38. Strings differ at index 21.
            Expected: "System.Globalization.UmAlQuraCalendar"
            But was:  "System.Globalization.GregorianCalendar"
            --------------------------------^
                at LinkAll.Calendars.CalendarTest.UmAlQura() in [...]/xamarin-macios/tests/linker/ios/link all/CalendarTest.cs:line 21

tests/linker/ios/link all/CalendarTest.cs

@@ -10,6 +10,9 @@ namespace LinkAll.Calendars {
 	[TestFixture]
 	// we want the tests to be available because we use the linker
 	[Preserve (AllMembers = true)]
+#if NET
+	[Ignore ("No globalization data yet - https://github.com/xamarin/xamarin-macios/issues/8906")]
+#endif
 	public class CalendarTest {
 
 		// application *MUST* be build with I18N.MidEast and I18N.Other (Thai)