Include default client settings in Datastream ITs (#107740)

In #107341 we added a new system property that is used to config the
rest client in rest integration tests.

This commit changes two datastream ITs to include the default client
settings so that this property is effective.

modules/data-streams/src/javaRestTest/java/org/elasticsearch/datastreams/LazyRolloverDataStreamIT.java

@@ -71,7 +71,7 @@ public class LazyRolloverDataStreamIT extends ESRestTestCase {
     private Settings simpleUserRestClientSettings() {
         // Note: This user is assigned the role "under_privilged". That role is defined in roles.yml.
         String token = basicAuthHeaderValue("test_simple_user", new SecureString(PASSWORD.toCharArray()));
-        return Settings.builder().put(ThreadContext.PREFIX + ".Authorization", token).build();
+        return Settings.builder().put(super.restClientSettings()).put(ThreadContext.PREFIX + ".Authorization", token).build();
     }
 
     @Before

modules/data-streams/src/javaRestTest/java/org/elasticsearch/datastreams/lifecycle/DataStreamLifecyclePermissionsTestCase.java

@@ -97,13 +97,13 @@ public abstract class DataStreamLifecyclePermissionsTestCase extends ESRestTestC
     Settings restPrivilegedClientSettings() {
         // Note: This user is assigned the role "under_privilged". That role is defined in roles.yml.
         String token = basicAuthHeaderValue("test_data_stream_lifecycle", new SecureString(PASSWORD.toCharArray()));
-        return Settings.builder().put(ThreadContext.PREFIX + ".Authorization", token).build();
+        return Settings.builder().put(super.restClientSettings()).put(ThreadContext.PREFIX + ".Authorization", token).build();
     }
 
     Settings restUnprivilegedClientSettings() {
         // Note: This user is assigned the role "under_privilged". That role is defined in roles.yml.
         String token = basicAuthHeaderValue("test_non_privileged", new SecureString(PASSWORD.toCharArray()));
-        return Settings.builder().put(ThreadContext.PREFIX + ".Authorization", token).build();
+        return Settings.builder().put(super.restClientSettings()).put(ThreadContext.PREFIX + ".Authorization", token).build();
     }
 
     @Before