[FIR] Union CFG edges from postponed lambdas only if outer call was analyzed independently

Before this change nodes unification was called if outer call was
  completed in the FULL mode, but it may happen even if this call is
  actually a part of some other outer call

compiler/fir/analysis-tests/testData/resolve/cfg/flowFromInplaceLambda.fir.txt

@@ -84,7 +84,7 @@ FILE: flowFromInplaceLambda.kt
             ^ (R|<local>/x| as R|kotlin/Int|)
         }
         )), (R|<local>/y| as R|kotlin/Int|), R|/exactlyOnce|<R|kotlin/Int|>(<L> = exactlyOnce@fun <anonymous>(): R|kotlin/Int| <inline=NoInline, kind=EXACTLY_ONCE>  {
-            R|<local>/x|.R|kotlin/Int.inc|()
+            R|<local>/x|.<Unresolved name: inc>#()
             R|<local>/y|.R|kotlin/Int.inc|()
             ^ Int(1)
         }
@@ -98,7 +98,7 @@ FILE: flowFromInplaceLambda.kt
             ^ (R|<local>/x| as R|kotlin/Int|)
         }
         )), (R|<local>/y| as R|kotlin/Int|), R|/atLeastOnce|<R|kotlin/Int|>(<L> = atLeastOnce@fun <anonymous>(): R|kotlin/Int| <inline=NoInline, kind=AT_LEAST_ONCE>  {
-            R|<local>/x|.R|kotlin/Int.inc|()
+            R|<local>/x|.<Unresolved name: inc>#()
             R|<local>/y|.R|kotlin/Int.inc|()
             ^ Int(1)
         }

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

@@ -39,7 +39,7 @@ fun completedCallExactlyOnce(x: Any?, y: Any?) {
         // The value of the type argument is known, so the call is complete and the data can flow.
         id(exactlyOnce { y.<!UNRESOLVED_REFERENCE!>inc<!>(); x as Int }),
         y as Int,
-        exactlyOnce { x.inc(); y.inc(); 1 }
+        exactlyOnce { x.<!UNRESOLVED_REFERENCE!>inc<!>(); y.inc(); 1 }
     ).inc() // OK
     x.inc() // OK
     y.inc() // OK
@@ -49,7 +49,7 @@ fun completedCallAtLeastOnce(x: Any?, y: Any?) {
     select(
         id(atLeastOnce { y.<!UNRESOLVED_REFERENCE!>inc<!>(); x as Int }),
         y as Int,
-        atLeastOnce { x.inc(); y.inc(); 1 }
+        atLeastOnce { x.<!UNRESOLVED_REFERENCE!>inc<!>(); y.inc(); 1 }
     ).inc() // OK
     x.inc() // OK
     y.inc() // OK