Restrict nodes for testClusterPrimariesActive1 (#90191)

This test sets up one `green` and one `yellow` index and requires that
the `green` index is the one that gets rebalanced. This may not be true
in future, but we can make it true by restricting the nodes that can
hold shards of the `yellow` index.

Also reverts #90184 which applied this fix to the wrong test :/

server/src/test/java/org/elasticsearch/cluster/routing/allocation/ClusterRebalanceRoutingTests.java

@@ -134,7 +134,17 @@ public class ClusterRebalanceRoutingTests extends ESAllocationTestCase {
 
         Metadata metadata = Metadata.builder()
             .put(IndexMetadata.builder("test1").settings(settings(Version.CURRENT)).numberOfShards(1).numberOfReplicas(1))
-            .put(IndexMetadata.builder("test2").settings(settings(Version.CURRENT)).numberOfShards(1).numberOfReplicas(1))
+            .put(
+                IndexMetadata.builder("test2")
+                    .settings(
+                        settings(Version.CURRENT).put(
+                            IndexMetadata.INDEX_ROUTING_INCLUDE_GROUP_SETTING.getConcreteSettingForNamespace("_id").getKey(),
+                            "node1,node2"
+                        )
+                    )
+                    .numberOfShards(1)
+                    .numberOfReplicas(1)
+            )
             .build();
 
         RoutingTable initialRoutingTable = RoutingTable.builder()
@@ -229,17 +239,7 @@ public class ClusterRebalanceRoutingTests extends ESAllocationTestCase {
 
         Metadata metadata = Metadata.builder()
             .put(IndexMetadata.builder("test1").settings(settings(Version.CURRENT)).numberOfShards(1).numberOfReplicas(1))
-            .put(
-                IndexMetadata.builder("test2")
-                    .settings(
-                        settings(Version.CURRENT).put(
-                            IndexMetadata.INDEX_ROUTING_INCLUDE_GROUP_SETTING.getConcreteSettingForNamespace("_id").getKey(),
-                            "node1,node2"
-                        )
-                    )
-                    .numberOfShards(1)
-                    .numberOfReplicas(1)
-            )
+            .put(IndexMetadata.builder("test2").settings(settings(Version.CURRENT)).numberOfShards(1).numberOfReplicas(1))
 
             .build();