[Test] Disable UNUSED_* diagnostics in tests which are not belong to contolFlowAnalysis suite

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2125.kt

@@ -1,12 +1,13 @@
+// FIR_IDENTICAL
 //KT-2125 Inconsistent error message on UNSAFE_CALL
 
 package e
 
 fun main() {
-    val <!UNUSED_VARIABLE!>compareTo<!> = 1
+    val compareTo = 1
     val s: String? = null
     s<!UNSAFE_CALL!>.<!>compareTo("")
 
-    val <!UNUSED_VARIABLE!>bar<!> = 2
+    val bar = 2
     s.<!UNRESOLVED_REFERENCE!>bar<!>()
 }