Improve Top Hit aggregation "field" names

[timroes]

Currently the top hit aggregation in the visualize editor has two fields, labeled "Field", without any further explanation. This can be very confusing and it would make sense improving this form slightly:

The first "Field" selector allows selecting which field the value should be taken from (and then also how to aggregate the value in case we get the last n (in the screenshot 100) values from this field. For numerical fields this can be an aggregation like avg/sum, for strings it can be concatenated.

The second "Field" is belonging with the "Order" and actually defining by which field the documents are sorted to retrieve the top n from it (often users will use a timestamp here descending to get the last x documents matching).

I would suggest we rename those labels slightly, to something like "Order Field" and "Value Field", and give them a help icon with a tooltip, giving some short description how they behave?

@cchaos @gchaps either of you have some input for this?

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[tsullivan]

The second "Field" is belonging with the "Order" and actually defining by which field the documents are sorted to retrieve the top n from it (often users will use a timestamp here descending to get the last x documents matching).

Thanks, I never would have guessed this!

[gchaps]

Here's a suggestion:

Value field
The field to use to calculate the metrics aggregation.

Order field
The field from which to retrieve and order the top documents.

[sulemanof]

Hey!
This was broken in #42130 after introducing the FieldParamType, which set the FieldParamEditor as a component for all of field type params.
But after merging the #55612 this will be fixed back:

If the above suggestion will be still relevant, I'll create a PR after merging #55612

[wylieconlon]

Looks like this is affecting users in 7.5, if I'm reading this correctly: https://discuss.elastic.co/t/kibanas-top-hits-aggregation-sort-by-field-broken/216971

[flash1293]

@sulemanof can this issue be closed? Seems like #56367 fixed it, right?

[sulemanof]

@flash1293
If the design team is OK with labels, and the suggestion to rename labels is not relevant after the fix:

Here's a suggestion:
Value field
The field to use to calculate the metrics aggregation.
Order field
The field from which to retrieve and order the top documents.

Then yes, it can be closed.

[flash1293]

@gchaps Do you think the current state is fine?

[gchaps]

@flash1293 Yes, I think the current state is ok.