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
CloseIndexClusterStateUpdateRequest request,
        Map<Index, ClusterBlock> blockedIndices,
        Map<Index, CloseIndexResponse.IndexResult> verifyResults,
        ActionListener<CloseIndexResponse> listener
    ) implements ClusterStateTaskListener {
        @Override
        public void onFailure(Exception e) {
            listener.onFailure(e);
        }
        @Override
        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
            assert false : "not called";
        }
    }
    /**
     * Step 1 - Start closing indices by adding a write block
     *
     * This step builds the list of indices to close (the ones explicitly requested that are not in CLOSE state) and adds a unique cluster
     * block (or reuses an existing one) to every index to close in the cluster state. After the cluster state is published, the shards
     * should start to reject writing operations and we can proceed with step 2.
     */
    static ClusterState addIndexClosedBlocks(
        final Index[] indices,
        final Map<Index, ClusterBlock> blockedIndices,
        final ClusterState currentState
    ) {
        final Set<Index> indicesToClose = new HashSet<>();
        for (Index index : indices) {
            final IndexMetadata indexMetadata = currentState.metadata().getIndexSafe(index);
            if (indexMetadata.getState() != IndexMetadata.State.CLOSE) {