[TD] Mute some javac tests or update their testdata

There was a refactoring of AbstractDiagnosticsTest in 9052ef06 which
  contains bug that `setupEnvironment` for AbstractDiagnosticsTestUsingJavac
  was not called, so for last year tests `UsingJavac` had no difference
  with usual diagnostics tests which causes some contradictions in test data

compiler/testData/diagnostics/tests/valueClasses/identityComparisonWithValueClasses.fir.kt

@@ -1,3 +1,4 @@
+// !SKIP_JAVAC
 // !LANGUAGE: +InlineClasses
 // !DIAGNOSTICS: -UNUSED_VARIABLE
 
@@ -25,4 +26,4 @@ fun test(f1: Foo, f2: Foo, b1: Bar, fn1: Foo?, fn2: Foo?) {
     val d2 = f1 === any || f1 !== any
     val d3 = any === fn1 || any !== fn1
     val d4 = fn1 === any || fn1 !== any
-}
+}