Disable a test that fails with ICU-76 (#1151)

The behavior regarding parsing a POSIX string will change in ICU-76. While we haven't updated ICU dependency to ICU-76 yet, test will fail when we do. Disable the test for now.

I'll follow up with ICU owners to figure out the expected behavior and update the test or implementation if needed.

resolves 143438257

Author: itingliu

Tests/FoundationInternationalizationTests/LocaleComponentsTests.swift

@@ -171,6 +171,7 @@ final class LocaleComponentsTests: XCTestCase {
             return comps
         }
 
+#if FIXED_ICU76_POSIX_VARIANT
         verify("en-US-u-ca-japanese-cu-eur-va-posix-tz-brrbr-ms-metric") {
             var comps = Locale.Components(languageCode: "en", languageRegion: "US")
             comps.calendar = .japanese
@@ -180,6 +181,7 @@ final class LocaleComponentsTests: XCTestCase {
             comps.measurementSystem = .metric
             return comps
         }
+#endif
 
         verify("de-DE-u-co-phonebk") {
             var comps = Locale.Components(languageCode: .german, languageRegion: .germany)