FIR CFG: remove ordering from control flow through in-place lambdas

Old graph:

  arg -> lambda enter -> ... -> lambda exit -> lambda enter -> ... ->
   -> lambda exit -> call

New graph:

  arg -+-> lambda enter -> ... -> lambda exit -+-> call
       \-> lambda enter -> ... -> lambda exit -/

compiler/fir/analysis-tests/testData/resolve/cfg/flowFromTwoInplaceLambdas.kt

@@ -75,7 +75,7 @@ fun test5(x: Any?, q: String?) {
 fun test6() {
     val x: String
     // not necessarily initialized in second lambda (may call in any order)
-    run2({ x = ""; x.length }, { x.length })
+    run2({ x = ""; x.length }, { <!UNINITIALIZED_VARIABLE!>x<!>.length })
     x.length // initialized here
 }