[8.x] [ES|QL] Enable suggestions for CHANGE_POINT command (#218100) (#218124)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[ES|QL] Enable suggestions for `CHANGE_POINT` command
(#218100)](#218100)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Dima
Arnautov","email":"[email protected]"},"sourceCommit":{"committedDate":"2025-04-14T14:12:45Z","message":"[ES|QL]
Enable suggestions for `CHANGE_POINT` command (#218100)\n\n##
Summary\n\nWith the `CHANGE_POINT` command moved to tech preview
(PR\nhttps://github.com/elastic/elasticsearch/pull/126407), we can
enable\nsuggestions in the
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Enable suggestions for `CHANGE_POINT`
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Enable suggestions for `CHANGE_POINT` command (#218100)\n\n##
Summary\n\nWith the `CHANGE_POINT` command moved to tech preview
(PR\nhttps://github.com/elastic/elasticsearch/pull/126407), we can
enable\nsuggestions in the
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Enable suggestions for `CHANGE_POINT` command (#218100)\n\n##
Summary\n\nWith the `CHANGE_POINT` command moved to tech preview
(PR\nhttps://github.com/elastic/elasticsearch/pull/126407), we can
enable\nsuggestions in the
editor.","sha":"1a6cea558964a87255d2a00ca58e62d914a55c80"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Dima Arnautov <[email protected]>

Author: kibanamachine

src/platform/packages/shared/kbn-esql-validation-autocomplete/src/definitions/commands.ts

@@ -590,7 +590,6 @@ export const commandDefinitions: Array<CommandDefinition<any>> = [
     suggest: suggestForJoin,
   },
   {
-    hidden: true,
     name: 'change_point',
     preview: true,
     description: i18n.translate(