Fix warnings in stdlib samples and test modules

libraries/stdlib/samples/test/samples/collections/collections.kt

@@ -599,6 +599,7 @@ class Collections {
         }
 
         @Sample
+        @Suppress("UNUSED_VARIABLE")
         fun firstNotNullOf() {
             data class Rectangle(val height: Int, val width: Int) {
                 val area: Int get() = height * width

libraries/stdlib/samples/test/samples/properties/delegates.kt

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+@file:Suppress("UNUSED_ANONYMOUS_PARAMETER")
+
 package samples.properties
 
 import kotlin.properties.Delegates