Shift ReferencesToSyntheticJavaProperties feature release from 1.9 to 2.1

Other related tests:
- testGenericJavaProperty
- testFunInterfaceConstructorReference

Meta issue: KT-8575
Review: https://jetbrains.team/p/kt/reviews/9595

UnsupportedSyntheticCallableReferenceChecker only existed for K1,
because we wanted to release the feature for 1.9 and the feature should
have been working for K2 unconditionally. But since, we're postponing
the release until 2.1, we also need to port the checker from K1 to K2

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -273,7 +273,6 @@ enum class LanguageFeature(
     DataObjects(KOTLIN_1_9), // KT-4107
     ProhibitAccessToEnumCompanionMembersInEnumConstructorCall(KOTLIN_1_9, kind = BUG_FIX), // KT-49110
     RefineTypeCheckingOnAssignmentsToJavaFields(KOTLIN_1_9, kind = BUG_FIX), // KT-46727
-    ReferencesToSyntheticJavaProperties(KOTLIN_1_9), // KT-8575
     ValueClassesSecondaryConstructorWithBody(sinceVersion = KOTLIN_1_9, kind = UNSTABLE_FEATURE), // KT-55333
     NativeJsProhibitLateinitIsInitializedIntrinsicWithoutPrivateAccess(KOTLIN_1_9, kind = BUG_FIX), // KT-27002
 
@@ -291,6 +290,8 @@ enum class LanguageFeature(
 
     // 2.1
 
+    ReferencesToSyntheticJavaProperties(KOTLIN_2_1), // KT-8575
+
     // End of 2.* language features --------------------------------------------------
 
     // This feature effectively might be removed because we decided to disable it until K2 and there it will be unconditionally enabled.