Disable rebalancing in searchable snapshots tests (#61068)

Fixes a test failure in which we allocated some shards and then
relocated them elsewhere, invalidating an assertion about the recovery
statistics which assumed that the shards stayed where they were
originally allocated.

Closes #61067.

Author: DaveCTurner

x-pack/plugin/searchable-snapshots/src/test/java/org/elasticsearch/xpack/searchablesnapshots/BaseSearchableSnapshotsIntegTestCase.java

@@ -28,7 +28,6 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.ByteSizeUnit;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.license.LicenseService;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.xpack.searchablesnapshots.cache.CacheService;
@@ -38,6 +37,8 @@
 import java.util.Collection;
 import java.util.List;
 
+import static org.elasticsearch.cluster.routing.allocation.decider.EnableAllocationDecider.CLUSTER_ROUTING_REBALANCE_ENABLE_SETTING;
+import static org.elasticsearch.license.LicenseService.SELF_GENERATED_LICENSE_TYPE;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.equalTo;
 
@@ -54,8 +55,10 @@ protected Collection<Class<? extends Plugin>> nodePlugins() {
 
     @Override
     protected Settings nodeSettings(int nodeOrdinal) {
-        final Settings.Builder builder = Settings.builder().put(super.nodeSettings(nodeOrdinal));
-        builder.put(LicenseService.SELF_GENERATED_LICENSE_TYPE.getKey(), "trial");
+        final Settings.Builder builder = Settings.builder()
+            .put(super.nodeSettings(nodeOrdinal))
+            .put(SELF_GENERATED_LICENSE_TYPE.getKey(), "trial")
+            .put(CLUSTER_ROUTING_REBALANCE_ENABLE_SETTING.getKey(), "none");
         if (randomBoolean()) {
             builder.put(
                 CacheService.SNAPSHOT_CACHE_SIZE_SETTING.getKey(),