[8.6] [Fleet] Fix open API for output to support logstash (elastic#14…

…6396) (elastic#146432)

# Backport

This will backport the following commits from `main` to `8.6`:
- [[Fleet] Fix open API for output to support logstash
(elastic#146396)](elastic#146396)

<!--- Backport version: 8.9.7 -->

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

<!--BACKPORT [{"author":{"name":"Nicolas
Chaulet","email":"nicolas.chaulet@elastic.co"},"sourceCommit":{"committedDate":"2022-11-28T16:23:50Z","message":"[Fleet]
Fix open API for output to support logstash
(elastic#146396)","sha":"a5c17d3d9aec59e366d70dfd4a5a14f04713b7df","branchLabelMapping":{"^v8.7.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","Team:Fleet","v8.6.0","v8.7.0"],"number":146396,"url":"https://github.com/elastic/kibana/pull/146396","mergeCommit":{"message":"[Fleet]
Fix open API for output to support logstash
(elastic#146396)","sha":"a5c17d3d9aec59e366d70dfd4a5a14f04713b7df"}},"sourceBranch":"main","suggestedTargetBranches":["8.6"],"targetPullRequestStates":[{"branch":"8.6","label":"v8.6.0","labelRegex":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v8.7.0","labelRegex":"^v8.7.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/146396","number":146396,"mergeCommit":{"message":"[Fleet]
Fix open API for output to support logstash
(elastic#146396)","sha":"a5c17d3d9aec59e366d70dfd4a5a14f04713b7df"}}]}]
BACKPORT-->

Co-authored-by: Nicolas Chaulet <nicolas.chaulet@elastic.co>

x-pack/plugins/fleet/common/openapi/components/schemas/output.yaml

@@ -11,7 +11,7 @@ properties:
     type: string
   type:
     type: string
-    enum: ['elasticsearch']
+    enum: ['elasticsearch', 'logstash']
   hosts:
     type: array
     items:
@@ -26,13 +26,13 @@ properties:
     type: string
   ssl:
     type: object
-    properties: 
-      certificate:
-        type: string
+    properties:
       certificate_authorities:
         type: array
         items:
           type: string
+      certificate:
+        type: string
       key:
         type: string
 required: