[LL FIR] AbstractInBlockModificationTest: add more tests

^KT-60518

analysis/low-level-api-fir/testdata/inBlockModification/insideDefaultParameter.kt

@@ -0,0 +1,7 @@
+class MyProducer {
+    fun produce(): Int = 4
+}
+
+fun MyProducer.testFun(param1: Int = <expr>produce</expr>()) {
+    42
+}