Merge boxWithJava testData into box, delete BoxWithJava test

compiler/testData/codegen/box/collections/irrelevantImplCharSequenceKotlin.kt

@@ -0,0 +1,30 @@
+// FILE: J.java
+
+public class J {
+    public static class A extends AImpl implements CharSequence {
+        public CharSequence subSequence(int start, int end) {
+            return null;
+        }
+    }
+}
+
+// FILE: test.kt
+
+abstract class AImpl {
+    fun charAt(index: Int): Char {
+        return 'A'
+    }
+
+    fun length(): Int {
+        return 56
+    }
+}
+
+class X : J.A()
+
+fun box(): String {
+    val x = X()
+    if (x.length != 56) return "fail 1"
+    if (x[0] != 'A') return "fail 2"
+    return "OK"
+}