Prepare for 2023.3: Don't use JDK_X in tests (#5417)

Recently, a new special language level X has been introduced to IntelliJ.
It's different from the other one, because it's an alway's preview level
(there's no non-preview version). Hence, we don't want to run a test
that distinguishes preview and non-preview on that particlar level.

JetBrains/intellij-community@89a73e9

java/tests/integrationtests/com/google/idea/blaze/java/sync/projectstructure/JdksTest.java

@@ -237,7 +237,7 @@ static class LanguageLevelWithPreview {
   @NotNull
   private static LanguageLevelWithPreview getLatestLevelWithPreview() {
     return stream(LanguageLevel.values())
-            .filter(it -> it.getPreviewLevel() != null)
+            .filter(it -> it.getPreviewLevel() != null && !it.getPreviewLevel().name().endsWith("_X"))
             .map(it -> new LanguageLevelWithPreview(it, it.getPreviewLevel()))
             .max(Comparator.comparingInt(it -> it.stableLevel.toJavaVersion().feature))
             .orElseThrow(() -> new RuntimeException("Test can't be run, no preview language levels found in this IntelliJ version"));