Fix test allocated processors test (#55429)

This test tries to set the number of allocated processors to seven. That
is fine, unless the test is running on a machine where
Runtime#availableProcessors is less than seven (typically when there are
fewer than seven logical cores, but it can happen in various other ways
related to CPU quotas in Docker containers with Docker-aware JVMs,
etc.). This commit addresses this by randomizing the number of allocated
processors, to a value that is less than or equal to the hard constraint
on the number of allocated processors.

Author: jasontedor

server/src/test/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsIT.java

@@ -210,12 +210,13 @@ public void testValuesSmokeScreen() throws IOException, ExecutionException, Inte
     }
 
     public void testAllocatedProcessors() throws Exception {
-        // start one node with 7 processors.
-        internalCluster().startNode(Settings.builder().put(EsExecutors.NODE_PROCESSORS_SETTING.getKey(), 7).build());
+        // the node.processors setting is bounded above by Runtime#availableProcessors
+        final int nodeProcessors = randomIntBetween(1, Runtime.getRuntime().availableProcessors());
+        internalCluster().startNode(Settings.builder().put(EsExecutors.NODE_PROCESSORS_SETTING.getKey(), nodeProcessors).build());
         waitForNodes(1);
 
         ClusterStatsResponse response = client().admin().cluster().prepareClusterStats().get();
-        assertThat(response.getNodesStats().getOs().getAllocatedProcessors(), equalTo(7));
+        assertThat(response.getNodesStats().getOs().getAllocatedProcessors(), equalTo(nodeProcessors));
     }
 
     public void testClusterStatusWhenStateNotRecovered() throws Exception {