Add remove_index_block arg to _create_from api

[parkertimmins]

Add a new boolean parameter remove_index_blocks from the _create_from API.
If this parameter is set to true, all index block will be filtered out when creating the destination index.
This will override any index block set in either the source index settings or the settings_override parameter.

Using this argument will be equivalent to passing

"settings_override": {
"index.blocks.write": null,
"index.blocks.read": null,
"index.blocks.read_only": null,
"index.blocks.read_only_allow_delete": null,
"index.blocks.metadata": null
}

This parameter will default to false.

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[elasticsearchmachine]

Hi @parkertimmins, I've created a changelog YAML for you.

[masseyke]

LGTM if this would be useful to the upgrade assistant. Just a reminder, we'll need to update the specification here: https://github.com/elastic/elasticsearch-specification/blob/main/specification/migrate/create_from/MigrateCreateFromRequest.ts#L45

[elasticsearchmachine]

💚 Backport successful

Status	Branch	Result
✅	8.x