Add restrictions for synthetic _source

[kilfoyle]

This adds the restrictions described in #1618 to the Enabling and disabling advanced indexing features for Fleet-managed data streams page.

I also removed some extra spacing which I must have added earlier by accident.

@lucabelluccini and @martijnvg, please check that I have the enable and disable code examples right, since I'm kind of guessing.

Closes: #1618

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[kilfoyle]

@lucabelluccini, @martijnvg Please let me know if the warning and code samples look okay.

Just trying to wrap things up since all docs PRs need to be merged by Jan.29. Thanks!

[martijnvg]

I left two comments.
Additionally in the screenshot, I see the _source.mode mapping attribute being used. Can this be removed in favor for the index.mapping.source.mode index setting?

[martijnvg]

Synthetic source is also supported on tsds data streams. I think this line can be removed?

[kilfoyle]

Thanks @martijnvg. I can remove the line, but from @lucabelluccini's issue: I've tested it on 8.17 and it's impossible to disable Synthetic _source on a TSDS data stream.

For now I've changed it to Note that disabling synthetic _source is supported only on non-TSDS data streams.
Please let me know if that's not what we want.

[martijnvg]

I commented on the issue: #1618 (comment)

Let's see what went wrong here.

[kilfoyle]

Thanks Martijn!

. Additionally in the screenshot, I see the _source.mode mapping attribute being used. Can this be removed in favor for the index.mapping.source.mode index setting?

Oops. I left the old version by accident so it's removed now.

Please see my other comment above about disabling synthetic _source.

[kilfoyle]

@martijnvg, @lucabelluccini Based on discussion in #1618 (comment) I've removed the note about disabling Synthetic _source not being supported on on TSDS data streams.

I've updated the PR description with the latest screen captures. Please let me know if it looks okay now. Thanks!

[karenzone]

LGTM 🎸