Fix for KT-14597: "When" over smartcasted enum is broken and breaks all other "when"

#KT-14597 Fixed

compiler/testData/codegen/bytecodeText/whenEnumOptimization/kt15806.kt

@@ -0,0 +1,27 @@
+
+private fun Any?.doTheThing(): String {
+    when (this) {
+        is String -> return this
+        is Level -> {
+            when (this) {
+                Level.O -> return Level.O.name
+                Level.K -> return Level.K.name
+            }
+        }
+
+        else -> return "fail"
+    }
+}
+
+
+enum class Level {
+    O,
+    K
+}
+
+
+fun box(): String {
+    return "O".doTheThing() + Level.K.doTheThing()
+}
+
+// 1 LOOKUPSWITCH