JVM_IR: keep the $default suffix for stubs for @JvmName functions

Technically a backwards compatibility problem, as the new backend
*consistently* renamed `f$default` on `f` with `@JvmName("g")` to
`g` instead of `g$default`, so it all worked out. However, this
breaks when encountering libraries compiled with the non-IR backend.

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -15091,6 +15091,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/jvmName/functionName.kt");
         }
 
+        @TestMetadata("functionWithDefault.kt")
+        public void testFunctionWithDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/jvmName/functionWithDefault.kt");
+        }
+
         @TestMetadata("loadJvmName.kt")
         public void testLoadJvmName() throws Exception {
             runTest("compiler/testData/codegen/box/jvmName/loadJvmName.kt");