When a shard becomes search active then trigger a refresh instead of waiting for the next scheduled refresh.
The `IndexShard#awaitShardSearchActive(...)` method registers a refresh listener and then often waits for the refresh scheduler to trigger a refresh. By default this is one second. In order to avoid increasing the query time of the Search API, the mentioned method should trigger a refresh instead for waiting it to happen.

As part of this change we also need to disable the refresh scheduler completely. Otherwise we run at risk of running two refreshes next after each other. One triggered from making shard search active and one from the refresh scheduler.  



server/src/main/java/org/elasticsearch/index/shard/IndexShard.java
);
                            /* Rolling the translog generation is not strictly needed here (as we will never have collisions between
                             * sequence numbers in a translog generation in a new primary as it takes the last known sequence number
                             * as a starting point), but it simplifies reasoning about the relationship between primary terms and
                             * translog generations.
                             */
                            engine.rollTranslogGeneration();
                            engine.fillSeqNoGaps(newPrimaryTerm);
                            replicationTracker.updateLocalCheckpoint(currentRouting.allocationId().getId(), getLocalCheckpoint());
                            primaryReplicaSyncer.accept(this, new ActionListener<ResyncTask>() {
                                @Override
                                public void onResponse(ResyncTask resyncTask) {
                                    logger.info("primary-replica resync completed with {} operations", resyncTask.getResyncedOperations());
                                    boolean resyncCompleted = primaryReplicaResyncInProgress.compareAndSet(true, false);
                                    assert resyncCompleted : "primary-replica resync finished but was not started";
                                }
                                @Override
                                public void onFailure(Exception e) {
                                    boolean resyncCompleted = primaryReplicaResyncInProgress.compareAndSet(true, false);
                                    assert resyncCompleted : "primary-replica resync finished but was not started";
                                    if (state == IndexShardState.CLOSED) {
                                        
                                    } else {
                                        try {
                                            failShard("exception during primary-replica resync", e);
                                        } catch (AlreadyClosedException ace) {
                                            
                                        }
                                    }
                                }