FIR: Add workaround for flatMap issue

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirOverloadByLambdaReturnTypeResolver.kt

@@ -38,10 +38,7 @@ class FirOverloadByLambdaReturnTypeResolver(
         allCandidates: Collection<Candidate>,
         bestCandidates: Set<Candidate>
     ): Set<Candidate> where T : FirStatement, T : FirResolvable {
-        if (
+        if (bestCandidates.size <= 1) return bestCandidates
-            bestCandidates.size <= 1 ||
-            !session.languageVersionSettings.supportsFeature(LanguageFeature.OverloadResolutionByLambdaReturnType)
-        ) return bestCandidates
 
         /*
          * Inference session may look into candidate of call, and for that it uses callee reference.

compiler/testData/diagnostics/testsWithStdLib/factoryPattern/overloadByLambdaReturnType_disabled.fir.kt

@@ -20,17 +20,17 @@ fun takeString(s: String) {}
 fun takeInt(s: Int) {}
 
 fun test_1() {
-    val x = <!AMBIGUITY!>create<!> { "" }
+    val x = create { "" }
     takeString(x)
 }
 
 fun test_2() {
-    val x = <!AMBIGUITY!>create<!> { 1 }
+    val x = create { 1 }
     takeInt(x)
 }
 
 fun test_3() {
-    val x = <!AMBIGUITY!>create<!> { 1.0 }
+    val x = create { 1.0 }
 }
 
 @OverloadResolutionByLambdaReturnType
@@ -38,11 +38,11 @@ fun <K> create(x: K, f: (K) -> Int): Int = 1
 fun <T> create(x: T, f: (T) -> String): String = ""
 
 fun test_4() {
-    val x = <!AMBIGUITY!>create<!>("") { "" }
+    val x = create("") { "" }
     takeString(x)
 }
 
 fun test_5() {
-    val x = <!AMBIGUITY!>create<!>("") { 1 }
+    val x = create("") { 1 }
     takeInt(x)
 }