Initialize TermsEnum eagerly (elastic#136279)

Temporary workaround for elastic#136268

Author: DaveCTurner

docs/changelog/136279.yaml

@@ -0,0 +1,5 @@
+pr: 136279
+summary: Initialize `TermsEnum` eagerly
+area: Search
+type: bug
+issues: []

server/src/main/java/org/elasticsearch/bootstrap/Elasticsearch.java

@@ -13,6 +13,7 @@
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.core.LoggerContext;
 import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.lucene.index.TermsEnum;
 import org.apache.lucene.util.Constants;
 import org.apache.lucene.util.StringHelper;
 import org.apache.lucene.util.VectorUtil;
@@ -220,6 +221,8 @@ private static void initPhase2(Bootstrap bootstrap) throws IOException {
         IfConfig.logIfNecessary();
 
         ensureInitialized(
+            // See https://github.com/elastic/elasticsearch/issues/136268
+            TermsEnum.class,
             // ReleaseVersions does nontrivial static initialization which should always succeed but load it now (before SM) to be sure
             ReleaseVersions.class,
             // ReferenceDocs class does nontrivial static initialization which should always succeed but load it now (before SM) to be sure