block-writes cannot be added after read-only (elastic#119007)

Fix bug in ReindexDataStreamIndexAction. If the source index has
both a block-writes and is read-only, these must be updated on
the destination index. If read-only is set first, the block-writes
cannot be added because settings cannot be modified.

docs/changelog/119007.yaml

@@ -0,0 +1,6 @@
+pr: 119007
+summary: Block-writes cannot be added after read-only
+area: Data streams
+type: bug
+issues:
+ - 119002

muted-tests.yml

@@ -293,8 +293,6 @@ tests:
   issue: https://github.com/elastic/elasticsearch/issues/118955
 - class: org.elasticsearch.repositories.blobstore.testkit.analyze.SecureHdfsRepositoryAnalysisRestIT
   issue: https://github.com/elastic/elasticsearch/issues/118970
-- class:  org.elasticsearch.xpack.migrate.action.ReindexDatastreamIndexTransportActionIT
-  issue: https://github.com/elastic/elasticsearch/issues/119002
 
 # Examples:
 #

x-pack/plugin/migrate/src/main/java/org/elasticsearch/xpack/migrate/action/ReindexDataStreamIndexTransportAction.java

@@ -92,8 +92,8 @@ protected void doExecute(
             .<AcknowledgedResponse>andThen(l -> deleteDestIfExists(destIndexName, l))
             .<AcknowledgedResponse>andThen(l -> createIndex(sourceIndex, destIndexName, l))
             .<BulkByScrollResponse>andThen(l -> reindex(sourceIndexName, destIndexName, l))
-            .<AddIndexBlockResponse>andThen(l -> addBlockIfFromSource(READ_ONLY, settingsBefore, destIndexName, l))
             .<AddIndexBlockResponse>andThen(l -> addBlockIfFromSource(WRITE, settingsBefore, destIndexName, l))
+            .<AddIndexBlockResponse>andThen(l -> addBlockIfFromSource(READ_ONLY, settingsBefore, destIndexName, l))
             .andThenApply(ignored -> new ReindexDataStreamIndexAction.Response(destIndexName))
             .addListener(listener);
     }