[ML Data Frame] Account for completed data frames in test (#42351)

When asserting on the checkpoint value if the DF has completed the checkpoint will be 1 else 0.
Similarly state may be started or indexing. Closes #42309

Author: davidkyle

x-pack/plugin/src/test/resources/rest-api-spec/test/data_frame/transforms_stats.yml

@@ -49,7 +49,7 @@ teardown:
   - match: { transforms.0.id: "airline-transform-stats" }
   - match: { transforms.0.state.indexer_state: "/started|indexing/" }
   - match: { transforms.0.state.task_state: "started" }
-  - match: { transforms.0.state.checkpoint: 0 }
+  - lte: { transforms.0.state.checkpoint: 1 }
   - lte: { transforms.0.stats.pages_processed: 1 }
   - match: { transforms.0.stats.documents_processed: 0 }
   - match: { transforms.0.stats.documents_indexed: 0 }
@@ -163,7 +163,7 @@ teardown:
         transform_id: "*"
   - match: { count: 2 }
   - match: { transforms.0.id: "airline-transform-stats" }
-  - match: { transforms.0.state.indexer_state: "started" }
+  - match: { transforms.0.state.indexer_state: "/started|indexing/" }
   - match: { transforms.1.id: "airline-transform-stats-dos" }
   - match: { transforms.1.state.indexer_state: "stopped" }