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

compiler/testData/diagnostics/tests/operatorsOverloading/AssignOperatorAmbiguity.kt

@@ -5,7 +5,7 @@ class MyInt(val i: Int) {
     operator fun plus(m: MyInt) : MyInt = MyInt(m.i + i)
 }
 
-operator fun Any.plusAssign(<!UNUSED_PARAMETER!>a<!>: Any) {}
+operator fun Any.plusAssign(a: Any) {}
 
 fun test(m: MyInt) {
     m += m
@@ -13,5 +13,3 @@ fun test(m: MyInt) {
     var i = 1
     i <!ASSIGN_OPERATOR_AMBIGUITY!>+=<!> 34
 }
-
-