Allow kibana_system user to manage .reindexed-v8-internal.alerts indices

[ymao1]

Existing built-in roles can manage .internal.alerts* and .internal.preview.alerts* indices. If created in 7.x, these indices will be reindexed for the 9.0 upgrade and receive the .reindexed-v8 prefix so adding those patterns to the same roles.

[elasticsearchmachine]

Hi @ymao1, I've created a changelog YAML for you.

[elasticsearchmachine]

Pinging @elastic/es-security (Team:Security)

[jakelandis]

If created in 7.x, these indices will be reindexed for the 9.0 upgrade

Shouldn't the result of the re-indexing via the Kibana upgrade assistant introduce an alias with the old name, which should allow continued access by the old name (without needing to add a new privilege) ?

[ymao1]

If created in 7.x, these indices will be reindexed for the 9.0 upgrade

Shouldn't the result of the re-indexing via the Kibana upgrade assistant introduce an alias with the old name, which should allow continued access by the old name (without needing to add a new privilege) ?

Yes, for the most part this works. There is a specific portion of our code that uses the alias to retrieve all the concrete backing indices and directly updates the mappings on these backing indices and this is the issue we're trying to address.

[jakelandis]

LGTM

[elasticsearchmachine]

💚 Backport successful

Status	Branch	Result
✅	8.x