Skips synonym test in mixed cluster bwc tests instead of YAML rest compat (#119044)

Author: carlosdelest

muted-tests.yml

@@ -216,9 +216,6 @@ tests:
 - class: org.elasticsearch.xpack.security.authc.AuthenticationServiceTests
   method: testInvalidToken
   issue: https://github.com/elastic/elasticsearch/issues/119019
-- class: org.elasticsearch.backwards.MixedClusterClientYamlTestSuiteIT
-  method: test {p0=synonyms/90_synonyms_reloading_for_synset/Reload analyzers for specific synonym set}
-  issue: https://github.com/elastic/elasticsearch/issues/116777
 - class: org.elasticsearch.xpack.security.authc.ldap.ActiveDirectoryRunAsIT
   issue: https://github.com/elastic/elasticsearch/issues/115727
 - class: org.elasticsearch.smoketest.DocsClientYamlTestSuiteIT

qa/mixed-cluster/build.gradle

@@ -70,6 +70,9 @@ excludeList.add('aggregations/percentiles_hdr_metric/Negative values test')
 // sync_id is removed in 9.0
 excludeList.add("cat.shards/10_basic/Help")
 
+// Can't work until auto-expand replicas is 0-1 for synonyms index
+excludeList.add("synonyms/90_synonyms_reloading_for_synset/Reload analyzers for specific synonym set")
+
 def clusterPath = getPath()
 
 buildParams.bwcVersions.withWireCompatible { bwcVersion, baseName ->