Fix testSearchAndRelocateConcurrently

This aims to test we can search through replica shard relocations.
However, the way the test was written it was sometimes also starting
another data node. The concurrent search requests would sometimes
hit this new node, before its cluster state was RECOVERED.

The search action throws exception when the cluster state is not
recovered as it needs to be able to read the cluster state.

This fixes the test to not start new data nodes.

muted-tests.yml

@@ -171,9 +171,6 @@ tests:
 - class: org.elasticsearch.search.basic.SearchWithRandomDisconnectsIT
   method: testSearchWithRandomDisconnects
   issue: https://github.com/elastic/elasticsearch/issues/116175
-- class: org.elasticsearch.search.basic.SearchWhileRelocatingIT
-  method: testSearchAndRelocateConcurrentlyRandomReplicas
-  issue: https://github.com/elastic/elasticsearch/issues/116145
 - class: org.elasticsearch.xpack.deprecation.DeprecationHttpIT
   method: testDeprecatedSettingsReturnWarnings
   issue: https://github.com/elastic/elasticsearch/issues/108628

server/src/internalClusterTest/java/org/elasticsearch/search/basic/SearchWhileRelocatingIT.java

@@ -119,7 +119,7 @@ public void run() {
             for (int j = 0; j < threads.length; j++) {
                 threads[j].start();
             }
-            allowNodes("test", between(1, 3));
+            allowNodes("test", between(1, 2));
             ClusterRerouteUtils.reroute(client());
             stop.set(true);
             for (int j = 0; j < threads.length; j++) {