update error message

Author: prwhelan

x-pack/plugin/security/qa/multi-cluster/src/javaRestTest/java/org/elasticsearch/xpack/remotecluster/RemoteClusterSecurityMlIT.java

@@ -200,7 +200,7 @@ public void testDataframeAnalyticsNotSupportForRemoteIndices() {
             """);
         final ResponseException e = expectThrows(ResponseException.class, () -> performRequestWithRemoteMlUser(putDataframeAnalytics));
         assertThat(e.getResponse().getStatusLine().getStatusCode(), equalTo(400));
-        assertThat(e.getMessage(), containsString("remote source indices are not supported"));
+        assertThat(e.getMessage(), containsString("remote source and cross-project indices are not supported"));
     }
 
     private Response performRequestWithRemoteMlUser(final Request request) throws IOException {

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/ml/data_frame_analytics_crud.yml

@@ -432,7 +432,7 @@ setup:
 "Test put config with remote source index":
 
   - do:
-      catch: /.*Validation Failed.* remote source indices are not supported/
+      catch: /.*Validation Failed.* remote source and cross-project indices are not supported/
       ml.put_data_frame_analytics:
         id: "config-with-missing-concrete-source-index"
         body: >