FIR: Do not use return statement for type of a block expression

Type of a block is a kind of irrelevant for lambdas: their type is much
more complicated and defined via FirDataFlowAnalyzer#returnExpressionsOfAnonymousFunction
at at FirCallCompleter.LambdaAnalyzerImpl#analyzeAndGetLambdaReturnArguments

compiler/fir/analysis-tests/testData/resolveWithStdlib/callableReferences/implicitTypes.fir.txt

@@ -11,6 +11,6 @@ FILE: implicitTypes.kt
     public final fun loop1(): R|(kotlin/Any?) -> kotlin/Nothing| {
         ^loop1 <Inapplicable(INAPPLICABLE): /use>#<R|kotlin/Any?|, R|kotlin/Nothing|>(::<Unresolved reference: loop2>#)
     }
-    public final fun loop2(): R|ERROR CLASS: cycle| {
+    public final fun loop2(): <ERROR TYPE REF: cycle> {
         ^loop2 R|/loop1|()
     }