[NI] Fix extracting type variables for flexible types in in captured types

Bug was introduced in b99efb because of lack of tests.
All code in `AbstractTypeCheckerContextForConstraintSystem.extractTypeVariableForSubtype`
  related to IN projection looks suspicious and needs further investigation

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -9548,6 +9548,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 runTest("compiler/testData/diagnostics/tests/inference/cannotCompleteResolveWithFunctionLiterals.kt");
             }
 
+            @TestMetadata("capturedInProjectedFlexibleType.kt")
+            public void testCapturedInProjectedFlexibleType() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/capturedInProjectedFlexibleType.kt");
+            }
+
             @TestMetadata("coerceFunctionLiteralToSuspend.kt")
             public void testCoerceFunctionLiteralToSuspend() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/inference/coerceFunctionLiteralToSuspend.kt");