Tolerate mixed types in sort

Author: davidkyle

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java

@@ -705,6 +705,7 @@ private SearchRequestBuilder createLatestDatafeedTimingStatsSearch(String indexN
             .setQuery(QueryBuilders.idsQuery().addIds(DatafeedTimingStats.documentId(jobId)))
             .addSort(
                 SortBuilders.fieldSort(DatafeedTimingStats.TOTAL_SEARCH_TIME_MS.getPreferredName())
+                    .setNumericType("double")
                     .unmappedType("double")
                     .order(SortOrder.DESC)
             );