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
.settings(Settings.builder().put(indexMetadata.getSettings()).put(VERIFIED_BEFORE_CLOSE_SETTING.getKey(), true))
                );
                routingTable.addAsFromOpenToClose(metadata.getSafe(index));
                logger.debug("closing index {} succeeded", index);
                closedIndices.add(index.getName());
            } catch (final IndexNotFoundException e) {
                logger.debug("index {} has been deleted since it was blocked before closing, ignoring", index);
            }
        }
        logger.info("completed closing of indices {}", closedIndices);
        return Tuple.tuple(
            ClusterState.builder(currentState).blocks(blocks).metadata(metadata).routingTable(routingTable).build(),
            List.copyOf(closingResults.values())
        );
    }
    public void openIndices(final OpenIndexClusterStateUpdateRequest request, final ActionListener<ShardsAcknowledgedResponse> listener) {
        onlyOpenIndices(request, listener.delegateFailure((delegate, response) -> {
            if (response.isAcknowledged()) {
                String[] indexNames = Arrays.stream(request.indices()).map(Index::getName).toArray(String[]::new);
                activeShardsObserver.waitForActiveShards(
                    indexNames,
                    request.waitForActiveShards(),
                    request.ackTimeout(),
                    shardsAcknowledged -> {
                        if (shardsAcknowledged == false) {
                            logger.debug(
                                "[{}] indices opened, but the operation timed out while waiting for enough shards to be started.",
                                Arrays.toString(indexNames)
                            );
                        }