FIR: disregard enhancements for warnings

Warnings are not implemented yet, so don't produce errors either.

compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/return/TypeParamOfClass.fir.txt

@@ -1,6 +1,6 @@
 public abstract interface TypeParamOfClass : R|kotlin/Any| {
     public abstract interface Sub<T : R|ft<kotlin/Any, kotlin/Any?>|> : R|test/TypeParamOfClass.Super<ft<T, T?>>| {
-        public abstract fun foo(): R|@EnhancedNullability T|
+        public abstract fun foo(): R|@EnhancedNullability T & Any|
 
     }
     public abstract interface Super<T : R|ft<kotlin/Any, kotlin/Any?>|> : R|kotlin/Any| {