[FIR] Fix TEST SPEC tests

Ensure the test data contents for both the frontends
are identical. This is needed for proper analysis of
K2-differences.

compiler/tests-spec/testData/diagnostics/notLinked/dfa/neg/30.fir.kt

@@ -1,6 +1,16 @@
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_VARIABLE -UNUSED_VALUE
 // SKIP_TXT
 
+/*
+ * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (NEGATIVE)
+ *
+ * SECTIONS: dfa
+ * NUMBER: 30
+ * DESCRIPTION: Raw data flow analysis test
+ * HELPERS: classes, objects, typealiases, functions, enumClasses, interfaces, sealedClasses
+ * ISSUES: KT-30907
+ */
+
 // TESTCASE NUMBER: 1
 class Case1(val x: Any?) {
     val y = x!!