[FIR2IR] Properly approximate intersection types during fir2ir conversion

^KT-62544 Fixed

compiler/testData/ir/irText/expressions/multipleSmartCasts.fir.kt.txt

@@ -14,9 +14,10 @@ fun test(x: Any) {
       x is IC1 -> x /*as IC1 */ is IC2
       else -> false
     } -> { // BLOCK
-      val tmp_0: Any = x /*as IC1 */
+      val tmp_0: Any = x
       val x1: Int = tmp_0 /*as IC1 */.component1()
-      val x2: String = tmp_0 /*as IC1 */ /*as IC2 */.component2()
+      val x2: String = tmp_0 /*as IC2 */.component2()
     }
   }
 }
+