Enable pattern-selection tests

Author: catamorphism

icu4c/source/test/intltest/messageformat2test_read_json.cpp

@@ -314,7 +314,7 @@ void TestMessageFormat2::jsonTestsFromFiles(IcuTestErrorCode& errorCode) {
 
     // Uncomment when test functions are implemented in the registry
     // See https://unicode-org.atlassian.net/browse/ICU-22907
-    // runTestsFromJsonFile(*this, "spec/pattern-selection.json", errorCode);
+    runTestsFromJsonFile(*this, "spec/pattern-selection.json", errorCode);
 
     // Do valid function tests
     runTestsFromJsonFile(*this, "spec/functions/date.json", errorCode);