[ML] Tolerate mixed types in datafeed stats sort (elastic#135096) (elastic#135372)

Author: davidkyle

docs/changelog/135096.yaml

@@ -0,0 +1,5 @@
+pr: 135096
+summary: Tolerate mixed types in datafeed stats sort
+area: Machine Learning
+type: bug
+issues: []

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)
             );