Add _meta information to built-in ILM policies

[dakrone]

We already ship templates that include the _meta map for things like component and composable
index templates, and we use the "managed": true indicator for many of our built-in items within
Elasticsearch.

This commit adds a description and managed flag to each of the ILM policies we ship by default.

[elasticmachine]

Pinging @elastic/es-core-features (Team:Core/Features)

[dakrone]

@elasticmachine update branch

[andreidan]

LGTM, thanks for working on this Lee

[elasticmachine]

Pinging @elastic/kibana-stack-management (Team:Stack Management)

[cjcenizal]

@dakrone Are these descriptions intended to be read by our end users, or intended for Elasticians? If they're intended for end users, can we sentence case this copy and run it by a writer? Can we also find a way to remove references to X-Pack, since that's no longer a term we expose our users to?

[dakrone]

@cjcenizal I think it depends on whether the UI consumes them, I was treating them as internal descriptions, but if they're intended to be visible in things like the UI then they should probably be more thought out :)

[cjcenizal]

Thanks Lee, that helps me understand. Do you think we should just hide managed policies entirely in the UI? Is there anything a user could gain from seeing them -- would they learn anything useful about policy configuration? Would seeing them answer any questions they might have about the behavior of the cluster?

[dakrone]

Do you think we should just hide managed policies entirely in the UI?

Not yet, we're not at a point where they can be ignored entirely by the user yet.

Is there anything a user could gain from seeing them -- would they learn anything useful about policy configuration?

Yes, especially things like the logs, metrics, and synthetics templates that we install out of the box. Those are things that a user should be aware of if they don't use Fleet, for instance.

Would seeing them answer any questions they might have about the behavior of the cluster?

Yes, especially related to the fleet stuff (like indexing into logs-*-* with adding an integration first)

[cjcenizal]

Great, thanks Lee. I think these are all strong arguments for surfacing the description in the UI, and refining that copy.