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

compiler/testData/diagnostics/tests/j+k/kt2890.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 //FILE:_03_collections/CollectionTest.java
 package _03_collections;
 
@@ -15,6 +16,6 @@ package _03_collections
 import java.util.ArrayList
 
 fun test() {
-  val <!UNUSED_VARIABLE!>c<!> = CollectionTest()
+  val c = CollectionTest()
   CollectionTest.add(ArrayList())
 }