Run 25_id_generation with and without synthetic id (elastic#142770)

* Run 25_id_generation with and without synthetic id

Add 25_id_generation_synthetic_id.yml as copy of 25_id_generation.yml
but with index.mapping.synthetic_id=true and updated expected id value.

Add synthetic id feature flag to ClientYamlTestSuiteIT

Harden 25_id_generation.yml to use synthetic_id=false

* Rename 25_id_generation_synthetic_id -> 26_id_...

* yaml tsdb/25_id_generation backwards compatible

Because tsdb/25_id_generation also runs in mixed and backwards
compatible cluster we cannot use synthetic_id setting at all unless the
cluster has cluster_features: "index.time_series_synthetic_id".

Introduce tsdb/26_id_generation_synthetic_id_false that specifically set
 the setting to false and otherwise keep the behaviour from
 25_generation_id.

26_id_generation_synthetic_id.yml is renamed to
27_id_generation_synthetic_id_true.yml

TL;DR:
Version <9.4 run 25_id_generation.yml
Version >=9.4 run 26_id_generation_synthetic_id_synthetic_false.yml and
27_id_generation_synthetic_id_true.yml

Author: burqen

rest-api-spec/src/yamlRestTest/java/org/elasticsearch/test/rest/ClientYamlTestSuiteIT.java

@@ -38,6 +38,7 @@ public class ClientYamlTestSuiteIT extends ESClientYamlSuiteTestCase {
         .feature(FeatureFlag.SYNTHETIC_VECTORS)
         .feature(FeatureFlag.RANDOM_SAMPLING)
         .feature(FeatureFlag.EXTENDED_DOC_VALUES_PARAMS)
+        .feature(FeatureFlag.TSDB_SYNTHETIC_ID_FEATURE_FLAG)
         .build();
 
     public ClientYamlTestSuiteIT(@Name("yaml") ClientYamlTestCandidate testCandidate) {

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/tsdb/25_id_generation.yml

@@ -4,6 +4,10 @@ setup:
       cluster_features: "gte_v8.14.0"
       reason: _tsid hashing introduced in 8.13 and tsid routing changed in 8.14
 
+  - skip:
+      cluster_features: "index.time_series_synthetic_id"
+      reason: when cluster has synthetic_id feature use 26_id_generation_synthetic_id_false instead
+
   - do:
       indices.create:
           index: id_generation_test