[Fleet] Find a better location in the UI for experimental indexing features

[kpollich]

Part of #132818

When we initially implemented the experimental data stream indexing toggles, we placed them in Fleet's policy editor UI under the advanced settings accordion mostly as a convenience. We didn't necessarily foresee the expanded functionality coming in the near future around these toggles and features.

Now, we've got a lot of toggles with lots of associated logic, and their current home on the policy editor is not really appropriate based on Fleet's information architecture. It doesn't make sense to edit datastream-level settings in a UI designed for editing policy-level settings.

There are a few approaches to consider here, I think:

1. Relocate the experimental toggles UI to another screen within the Fleet UI, likely the /data_streams page or the Integration settings screen
2. Contribute toggles to the stack management plugin so these settings can be toggled directly on component templates for data streams

Of these two options, number 2 seems like the most appropriate location. Editing data stream mappings/settings should ideally only happen in a single location within Kibana. Stack management should be the "source of truth" for these values.

The goals of moving these toggles are as follows:

• Provide these settings in a more predictable, grok-able location within Kibana's broader information architecture
• Provide an "escape hatch" for support engineers or users who might encounter problems with integrations that supply these experimental settings - e.g. ensure they can be disabled somewhere

Open to discussion about the best path forward here, of course!

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[jlind23]

@mukeshelastic Assigning this to you as it is TSDB related.

[kpollich]

This is a pretty far-off enhancement, and I don't think the product impact is very high. We'd need to contribute this to the stack management UI, and I think just deferring to the docs we're contributing in elastic/ingest-docs#151 is probably good enough for the foreseeable future. Ideally, users won't need to toggle these features on/off at all because they'll be stable and robust - they'll just be unnoticed "under the hood" optimizations we provide for our users 🙂

[jlind23]

Closing this as the toggles were removed: #155516