Update schema for new indexes

I commented on #2907367: Add indexes to important fields because that was easier.

Also, if that change is already in HEAD then this is imho at least a major bug.

Not *quite* the same, but you should just need to do something like this for each affected field:

/**
 * Update the status field.
 */
function paragraphs_update_8014() {
  // The status field was promoted to an entity key in paragraphs_update_8013(),
  // which makes it NOT NULL in the default SQL storage, which means its storage
  // definition needs to be updated as well.
  $entity_definition_update_manager = \Drupal::service('entity.definition_update_manager');
  $entity_definition_update_manager->updateFieldStorageDefinition($entity_definition_update_manager->getFieldStorageDefinition('status', 'paragraph'));
}

Looks good to me. The onEntityTypeUpdate() might have created the necessary indexes but didn't update the installed field storage definitions.

I'd love to have a better system for this in core that doesn't require custom storage schemas and this seems like a pretty nice start, but things get a bit more complicated once you need indexes that cover multiple fields or unique indexes, fields with multiple properties (e.g. not sure what would happen with the commerce implementation if you try to put an index on a price field).

I can confirm the RTBC. Thanks to all who worked on this!

Committed! Thanks!

I've found another field that needs indexing, adding it to field_indexes and the rerunning the update script does not add an index to the additional field, should it do? https://www.drupal.org/project/commerce/issues/3224681