Disable the maintenance of the {comment_entity_statistics} table when POSTing bulk docs.

With active comments statistics replication is failing with this error:

Drupal\Core\Database\IntegrityConstraintViolationException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'last_comment_uid' cannot be null: UPDATE {comment_entity_statistics} SET cid=:db_update_placeholder_0, comment_count=:db_update_placeholder_1, last_comment_timestamp=:db_update_placeholder_2, last_comment_name=:db_update_placeholder_3, last_comment_uid=:db_update_placeholder_4 WHERE ( (entity_id = :db_condition_placeholder_0) AND (entity_type = :db_condition_placeholder_1) AND (field_name = :db_condition_placeholder_2) ); Array ( [:db_update_placeholder_0] => 754 [:db_update_placeholder_1] => 1 [:db_update_placeholder_2] => 1469804379 [:db_update_placeholder_3] => [:db_update_placeholder_4] => [:db_condition_placeholder_0] => 357 [:db_condition_placeholder_1] => node [:db_condition_placeholder_2] => comment ) in Drupal\Core\Database\Connection->handleQueryException() (line 668 of /var/www/drupal8dev/core/lib/Drupal/Core/Database/Connection.php).

This can be fixed disabling the statistics when accessing the POST method for BulkDocs endpoint as we do on migration in Multiversion module.