IR: fix thisReceiver parameter type for function classes

Incorrect builder was used at line 269, which led to non-sensible type
in `IrClass.thisReceiver` for function types, such as
`SuspendFunction1<SuspendFunction1, SuspendFunction1>` in the linked
issue.

Avoid creating types manually completely to simplify this code and fix
the bug.

 #KT-49168 Fixed

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -7230,6 +7230,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/coroutines/kt24135.kt");
         }
 
+        @TestMetadata("kt49168.kt")
+        public void ignoreKt49168() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/kt49168.kt");
+        }
+
         @TestMetadata("suspendFunctionAsSupertype.kt")
         public void ignoreSuspendFunctionAsSupertype() throws Exception {
             runTest("compiler/testData/codegen/box/coroutines/suspendFunctionAsSupertype.kt");