[java] IDEA-381003 Prerequisite: do not resolve preview feature constant

It's absent in mockJDK, so we will have problems testing preview features
And in any case, we can skip this if we trust JDK (it will be even somewhat faster)

GitOrigin-RevId: 4fbe70db8964f61930b87927c0d71bd909ab810d

java/codeserver/core/src/com/intellij/java/codeserver/core/JavaPreviewFeatureUtil.java

@@ -185,11 +185,8 @@ public final class JavaPreviewFeatureUtil {
 
     PsiReferenceExpression referenceExpression = tryCast(feature.getDetachedValue(), PsiReferenceExpression.class);
     if (referenceExpression == null) return null;
-
-    PsiEnumConstant enumConstant = tryCast(referenceExpression.resolve(), PsiEnumConstant.class);
-    if (enumConstant == null) return null;
-
-    return JavaFeature.convertFromPreviewFeatureName(enumConstant.getName());
+    var referenceName = referenceExpression.getReferenceName();
+    return referenceName == null ? null : JavaFeature.convertFromPreviewFeatureName(referenceName);
   }
 
   @Contract(value = "null -> null", pure = true)