Update deprecation message in EnrichPolicy (#116504)

The `elasticsearch_version` property of enrich policies is deprecated
with a message saying that it will be removed in ES 9.0. It's still
deprecated, but it won't be removed in 9.0. So this change makes the
deprecation message less specific.

Author: PeteGillinElastic

x-pack/plugin/build.gradle

@@ -89,5 +89,6 @@ tasks.named("yamlRestCompatTestTransform").configure({ task ->
   task.skipTest("esql/80_text/reverse text", "The output type changed from TEXT to KEYWORD.")
   task.skipTest("esql/80_text/values function", "The output type changed from TEXT to KEYWORD.")
   task.skipTest("privileges/11_builtin/Test get builtin privileges" ,"unnecessary to test compatibility")
+  task.skipTest("enrich/10_basic/Test using the deprecated elasticsearch_version field results in a warning", "The deprecation message was changed")
 })
 

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/enrich/EnrichPolicy.java

@@ -36,7 +36,7 @@
 public final class EnrichPolicy implements Writeable, ToXContentFragment {
 
     private static final String ELASTICEARCH_VERSION_DEPRECATION_MESSAGE =
-        "the [elasticsearch_version] field of an enrich policy has no effect and will be removed in Elasticsearch 9.0";
+        "the [elasticsearch_version] field of an enrich policy has no effect and will be removed in a future version of Elasticsearch";
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(EnrichPolicy.class);
 

x-pack/plugin/enrich/qa/rest/build.gradle

@@ -32,3 +32,8 @@ testClusters.configureEach {
   setting 'xpack.security.enabled', 'false'
   requiresFeature 'es.index_mode_feature_flag_registered', Version.fromString("8.4.0")
 }
+
+tasks.named("yamlRestCompatTestTransform").configure({ task ->
+  task.skipTest("enrich/10_basic/Test using the deprecated elasticsearch_version field results in a warning", "The deprecation message was changed")
+})
+

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/enrich/10_basic.yml

@@ -69,7 +69,7 @@ setup:
 
   - do:
       warnings:
-        - "the [elasticsearch_version] field of an enrich policy has no effect and will be removed in Elasticsearch 9.0"
+        - "the [elasticsearch_version] field of an enrich policy has no effect and will be removed in a future version of Elasticsearch"
       enrich.put_policy:
         name: policy-crud-warning
         body: