Rename tests: boxWithJava -> boxAgainstJava

compiler/testData/codegen/boxAgainstJava/visibility/package/kt2781.java

@@ -0,0 +1,9 @@
+import java.lang.String;
+
+class J {
+    String value;
+
+    J(String value) {
+        this.value = value;
+    }
+}