JVM_IR KT-50076 don't null check moved dispatch receiver parameter

compiler/testData/codegen/bytecodeText/interfaces/noNullCheckOnThisInDefaultMethod.kt

@@ -0,0 +1,8 @@
+interface Test {
+    fun foo() = "abc"
+    fun String.bar() = "def"
+}
+
+// 1 check
+//  ^ no null check for dispatch receiver parameters in 'foo' and 'bar',
+//    extension receiver parameter in 'bar' is checked