[TEST] Migrate duplicating javac tests to new test runners

Also minimize scope of DiagnosticUsingJavac tests to
 `compiler/testData/diagnostics/tests/javac`. This is fine since
 javac compilation mode is still not finished and no one not going to
 support it

compiler/testData/diagnostics/tests/javac/inheritance/InheritanceAmbiguity2.kt

@@ -0,0 +1,30 @@
+// FILE: a/x.java
+package a;
+
+public class x {
+    public class Z {}
+}
+
+// FILE: a/i.java
+package a;
+
+public interface i {
+    public class Z {}
+}
+
+// FILE: a/i2.java
+package a;
+
+public interface i2 extends i {}
+
+// FILE: a/y.java
+package a;
+
+public class y extends x implements i2 {
+    public Z getZ() { return null; }
+}
+
+// FILE: test.kt
+package a
+
+fun test() = y().<!MISSING_DEPENDENCY_CLASS!>getZ<!>()