Switching log to warn (elastic#127729)

Author: jonathan-buttner

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/DatafeedJob.java

@@ -377,7 +377,7 @@ private void run(long start, long end, FlushJobAction.Request flushRequest) {
                 extractedData = result.data();
                 searchInterval = result.searchInterval();
             } catch (Exception e) {
-                LOGGER.error(() -> "[" + jobId + "] error while extracting data", e);
+                LOGGER.warn(() -> "[" + jobId + "] error while extracting data", e);
                 // When extraction problems are encountered, we do not want to advance time.
                 // Instead, it is preferable to retry the given interval next time an extraction
                 // is triggered.