cannot depend on list order

Author: masseyke

modules/data-streams/src/yamlRestTest/resources/rest-api-spec/test/data_stream/240_data_stream_settings.yml

@@ -57,7 +57,7 @@ setup:
   - match: { data_streams.0.name: my-data-stream-1 }
   - match: { data_streams.0.applied_to_data_stream: true }
   - match: { data_streams.0.index_settings_results.applied_to_data_stream_only: [index.number_of_shards]}
-  - match: { data_streams.0.index_settings_results.applied_to_data_stream_and_backing_indices: [index.lifecycle.name, index.lifecycle.prefer_ilm] }
+  - length: { data_streams.0.index_settings_results.applied_to_data_stream_and_backing_indices: 2  }
   - match: { data_streams.0.settings.index.number_of_shards: "2" }
   - match: { data_streams.0.settings.index.lifecycle.name: "my-new-policy" }
   - match: { data_streams.0.settings.index.lifecycle.prefer_ilm: "true" }