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
@Override
        @SuppressForbidden(reason = "consuming published cluster state for legacy reasons")
        public ClusterState execute(ClusterState currentState, List<TaskContext<CloseIndicesTask>> taskContexts) throws Exception {
            ClusterState state = currentState;
            for (final var taskContext : taskContexts) {
                final var task = taskContext.getTask();
                try {
                    final Tuple<ClusterState, List<IndexResult>> closingResult = closeRoutingTable(
                        state,
                        task.blockedIndices,
                        task.verifyResults
                    );
                    state = closingResult.v1();
                    final List<IndexResult> indices = closingResult.v2();
                    assert indices.size() == task.verifyResults.size();
                    taskContext.success(clusterState -> {
                        final boolean acknowledged = indices.stream().noneMatch(IndexResult::hasFailures);
                        final String[] waitForIndices = indices.stream()
                            .filter(result -> result.hasFailures() == false)
                            .filter(result -> clusterState.routingTable().hasIndex(result.getIndex()))
                            .map(result -> result.getIndex().getName())
                            .toArray(String[]::new);
                        if (waitForIndices.length > 0) {
                            activeShardsObserver.waitForActiveShards(
                                waitForIndices,