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

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2234.kt

@@ -18,8 +18,8 @@ fun main() {
 fun foo() {
     val x : Int? = 3
     if (x != null)  {
-        val <!UNUSED_VARIABLE!>u<!> = checkSubtype<Int>(x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>)
+        val u = checkSubtype<Int>(x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>)
         val y = checkSubtype<Int>(<!DEBUG_INFO_SMARTCAST!>x<!>)
-        val <!UNUSED_VARIABLE!>z<!> : Int = y
+        val z : Int = y
     }
 }