Tests: copy diagnostic test to codegen/box

This is basically a copy of the test
`diagnostics/tests/j+k/primitiveOverrides/triangleWithFlexibleTypeAndSubstitution4.kt`.
The diagnostic version of the test is not removed because it has
frontend-specific diagnostics `FIR_DUMP` and `SCOPE_DUMP`.

This test is copied to make it clear that it actually passes in K1, and
new errors in K2 here are technically a breaking change, see KT-66529.
The error CONFLICTING_INHERITED_JVM_DECLARATIONS was present there only
because diagnostic tests used parts of the old JVM backend to report JVM
backend diagnostics.

 #KT-66529

compiler/testData/codegen/box/javaInterop/triangleWithFlexibleTypeAndSubstitution4.kt

@@ -0,0 +1,28 @@
+// TARGET_BACKEND: JVM_IR
+
+// IGNORE_BACKEND_K2: JVM_IR
+// K2 status: KT-66529 K2: MANY_IMPL_MEMBER_NOT_IMPLEMENTED on inheriting Java member with generic type and Kotlin member with primitive type
+
+// FILE: A.java
+
+public class A<T> {
+    public String foo(T x) {
+        return "Fail";
+    }
+}
+
+// FILE: main.kt
+
+interface B<T> {
+    fun foo(x: T) = "OK"
+}
+
+open class C : A<Int>()
+
+interface D : B<Int>
+
+class E : C(), D
+
+fun box(): String {
+    return E().foo(42)
+}