Migrate all JDK 15 related tests to JDK 17

compiler/testData/codegen/boxModernJdk/testsWithJava17/sealed/sealedJavaClassViaJavaReflection.kt

@@ -0,0 +1,17 @@
+// WITH_REFLECT
+// FILE: Base.java
+public sealed class Base permits O, K {}
+
+// FILE: O.java
+public final class O extends Base {}
+
+// FILE: K.java
+public non-sealed class K extends Base {}
+
+// FILE: main.kt
+
+fun box(): String {
+    val clazz = Base::class.java
+    if (!clazz.isSealed) return "Error: Base is not sealed"
+    return clazz.permittedSubclasses.joinToString("") { it.simpleName ?: "_No name provided_" }
+}