[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/fieldsResolution/ConstantByFqName.kt

@@ -0,0 +1,16 @@
+// FIR_IDENTICAL
+// FILE: a/x.java
+package a;
+
+public class x {
+    public static class y {
+        public static final int I = 42;
+    }
+}
+
+// FILE: b/x.java
+package b;
+
+public class x {
+    public static final int I = a.x.y.I;
+}