[Discover] Always show unmapped fields

[majagrubic]

Summary

As per discussion, we'll always request unmapped fields when using the fields API. There will be no user-configurable switch in the UI and no data migration.

This PR removes the switch from the UI and removes the data migration. The unmappedFieldsConfig remains, but we can clean up the code in one of the following PRs.

Checklist

Delete any items that are not applicable to this PR.

- [ ] Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
- [ ] Documentation was added for features that require explanation or tutorials

• Unit or functional tests were updated or added to match the most common scenarios
  - [ ] Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
  - [ ] Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
  - [ ] If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
  - [ ] This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
  - [ ] This was checked for cross-browser compatibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[wylieconlon]

This PR looks like the right approach based on our latest discussion. The main thing that's missing is integration with the advanced settings.

Edit: I thought we would have an advanced setting related to unmapped fields. If we don't then this PR is the right scope.

[elasticmachine]

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

[flash1293]

@elasticmachine merge upstream

[flash1293]

Tested and unmapped fields are shown everywhere. LGTM

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 0887f87
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Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
discover	409.5KB	407.3KB	-2.1KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
discover	79.5KB	79.4KB	-47.0B

Saved Objects .kibana field count

Every field in each saved object type adds overhead to Elasticsearch. Kibana needs to keep the total field count below Elasticsearch's default limit of 1000 fields. Only specify field mappings for the fields you wish to search on or query. See https://www.elastic.co/guide/en/kibana/master/development-plugin-saved-objects.html#_mappings

id	before	after	diff
search	11	10	-1

History

• 💛 Build #107759 was flaky e264ce3
• 💚 Build #107587 succeeded e05f479
• 💔 Build #107440 failed 5d0d6f9

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream