[FIR] Increase level of sequential when branches

Level of CFGNode is used to determine which call is a common one for
  creating node with union of arguments (to merge flow from multiple
  in-place lambdas). Before this change calls in different when branches
  may have same node level, which entail passing smartcasts from moddle of
  one branch to another

```
val x: Any = ...
when {
    ... -> run { x as String } // (1)
    ... -> {
        run {
            x.foo()
        } // (2)
        "hello"
    }
}
```

Call `(1)` was assumed as argument of call `(2)` which is incorrect

#KT-44814 Fixed

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -29916,6 +29916,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/smartCasts/kt44804.kt");
         }
 
+        @TestMetadata("kt44814.kt")
+        public void testKt44814() throws Exception {
+            runTest("compiler/testData/codegen/box/smartCasts/kt44814.kt");
+        }
+
         @TestMetadata("lambdaArgumentWithoutType.kt")
         public void testLambdaArgumentWithoutType() throws Exception {
             runTest("compiler/testData/codegen/box/smartCasts/lambdaArgumentWithoutType.kt");