KT-47475 Do not copy InnerClass attribute for WhenMapping classes

compiler/testData/codegen/box/when/kt47475.kt

@@ -0,0 +1,27 @@
+// TARGET_BACKEND: JVM
+// CHECK_BYTECODE_TEXT
+
+// MODULE: lib
+// FILE: lib.kt
+
+enum class SomeEnum{A, B}
+
+inline fun inlineEnumWhen(someEnum: SomeEnum) = when(someEnum) {
+    SomeEnum.A -> "A"
+    else -> "not A"
+}
+
+// JVM_IR_TEMPLATES
+// 2 INNERCLASS
+
+// MODULE: caller(lib)
+// FILE: caller.kt
+
+fun box(): String {
+    inlineEnumWhen(SomeEnum.A)
+    val mappings = Class.forName("CallerKt\$box\$\$inlined\$inlineEnumWhen\$1\$wm\$LibKt\$WhenMappings")
+    return if (mappings.enclosingClass == null) "OK" else "FAIL"
+}
+
+// JVM_IR_TEMPLATES
+// 0 INNERCLASS