[FIR] Fix copy paste error in receiver enhancement

compiler/testData/diagnostics/tests/j+k/receiverEnhancement.kt

@@ -0,0 +1,23 @@
+// FIR_IDENTICAL
+// FILE: J.java
+public class J extends Foo {
+    @Override
+    public <T> T bar(String $this$bar) {
+        super.bar($this$bar);
+    }
+}
+
+// FILE: test.kt
+open class Foo {
+    fun <T> String.bar(): T {
+        @Suppress("UNCHECKED_CAST")
+        return null as T
+    }
+}
+
+fun J.test(s1: String?, s2: String) {
+    s1<!UNSAFE_CALL!>.<!>bar<Int>()
+    s1?.bar<Int>()
+    s2.bar<Int>()
+    s2<!UNNECESSARY_SAFE_CALL!>?.<!>bar<Int>()
+}