Fix testFollowerCheckerDetectsUnresponsiveNodeAfterMasterReelection (#84200)

This test would fail if we introduce the network partition while the
master is still publishing a cluster state update and hasn't received
the ack from the victim node. In this case the default publish timeout
means that the master will wait for 30s before completing the stalled
publication and moving on to the `node-left` one, but
`ensureStableCluster` also times out after 30s which leaves not much
time for the master to remove the victim node.

This commit reduces the publish timeout to 10s so that the master
recovers well before `ensureStableCluster` times out.

Closes #84172

Author: DaveCTurner

server/src/internalClusterTest/java/org/elasticsearch/discovery/StableMasterDisruptionIT.java

@@ -128,6 +128,7 @@ public void testFollowerCheckerDetectsUnresponsiveNodeAfterMasterReelection() th
                 .put(LeaderChecker.LEADER_CHECK_RETRY_COUNT_SETTING.getKey(), "4")
                 .put(FollowersChecker.FOLLOWER_CHECK_TIMEOUT_SETTING.getKey(), "1s")
                 .put(FollowersChecker.FOLLOWER_CHECK_RETRY_COUNT_SETTING.getKey(), 1)
+                .put(Coordinator.PUBLISH_TIMEOUT_SETTING.getKey(), "10s")
                 .build()
         );
     }