Allow ServiceIntegrationTest.smokeTest to work with session-based credentials.

Author: millems

services/iam/src/it/java/software/amazon/awssdk/services/iam/ServiceIntegrationTest.java

@@ -37,6 +37,6 @@ public void setUp() {
 
     @Test
     public void smokeTest() {
-        assertThat(iam.listAccessKeys().accessKeyMetadata()).isNotNull();
+        assertThat(iam.listUsers().users()).isNotNull();
     }
 }