Tiny supportability nit: today we emit these log messages when adding a write block to an index:

```
[2022-03-22T19:43:26,897][INFO ][o.e.c.m.MetadataIndexStateService] [node_t1] adding block write to indices [[test-blocks/eLkrYpm_S3WNemfWpXrhPA]]
[2022-03-22T19:43:26,933][INFO ][o.e.c.m.MetadataIndexStateService] [node_t1] completed adding block write to indices [test-blocks]
```

This is kind of confusing, a `block write` sounds like we're writing a block of data. It's not clear that `write` is variable (we also say `block read`) or the name of a block setting. I think we should word this as `adding [index.blocks.write] block to indices` instead.
server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexStateService.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.cluster.metadata;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.Version;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRunnable;
import org.elasticsearch.action.NotifyOnceListener;
import org.elasticsearch.action.admin.indices.close.CloseIndexClusterStateUpdateRequest;
import org.elasticsearch.action.admin.indices.close.CloseIndexResponse;
import org.elasticsearch.action.admin.indices.close.CloseIndexResponse.IndexResult;
import org.elasticsearch.action.admin.indices.close.CloseIndexResponse.ShardResult;
import org.elasticsearch.action.admin.indices.close.TransportVerifyShardBeforeCloseAction;
import org.elasticsearch.action.admin.indices.open.OpenIndexClusterStateUpdateRequest;
import org.elasticsearch.action.admin.indices.readonly.AddIndexBlockClusterStateUpdateRequest;
import org.elasticsearch.action.admin.indices.readonly.AddIndexBlockResponse;
import org.elasticsearch.action.admin.indices.readonly.AddIndexBlockResponse.AddBlockResult;
import org.elasticsearch.action.admin.indices.readonly.AddIndexBlockResponse.AddBlockShardResult;
import org.elasticsearch.action.admin.indices.readonly.TransportVerifyShardIndexBlockAction;
import org.elasticsearch.action.support.ActiveShardsObserver;
import org.elasticsearch.action.support.master.AcknowledgedResponse;
import org.elasticsearch.action.support.master.ShardsAcknowledgedResponse;