[9.2] [DOCS] Fix OpenAPI error in OpenAI connector secrets (#244679) (#245154)

# Backport

This will backport the following commits from `main` to `9.2`:
- [[DOCS] Fix OpenAPI error in OpenAI connector secrets
(#244679)](#244679)

<!--- Backport version: 10.2.0 -->

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

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Fix OpenAPI error in OpenAI connector secrets
(#244679)","sha":"ea6462079e0f332141a623330595c46d7085fab7","branchLabelMapping":{"^v9.3.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["Team:Docs","release_note:skip","docs","backport:version","v9.3.0","v8.19.8","v9.2.2"],"title":"[DOCS]
Fix OpenAPI error in OpenAI connector
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Fix OpenAPI error in OpenAI connector secrets
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Fix OpenAPI error in OpenAI connector secrets
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BACKPORT-->

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

Author: lcawl

oas_docs/output/kibana.serverless.yaml

@@ -86859,7 +86859,6 @@ components:
           description: |
             Base64-encoded PEM CA certificate content for PKI authentication (Other provider only). Optional.
           minLength: 1
-      required: []
     opsgenie_secrets:
       title: Connector secrets properties for an Opsgenie connector
       required:

oas_docs/output/kibana.yaml

@@ -98168,7 +98168,6 @@ components:
           description: |
             Base64-encoded PEM CA certificate content for PKI authentication (Other provider only). Optional.
           minLength: 1
-      required: []
     opsgenie_secrets:
       title: Connector secrets properties for an Opsgenie connector
       required:

src/platform/packages/private/kbn-validate-oas/oas_error_baseline.json

@@ -1,4 +1,4 @@
 {
-  "./oas_docs/output/kibana.yaml": 60,
-  "./oas_docs/output/kibana.serverless.yaml": 268
+  "./oas_docs/output/kibana.yaml": 59,
+  "./oas_docs/output/kibana.serverless.yaml": 267
 }

x-pack/platform/plugins/shared/actions/docs/openapi/components/schemas/genai_secrets.yaml

@@ -23,4 +23,3 @@ properties:
     description: |
       Base64-encoded PEM CA certificate content for PKI authentication (Other provider only). Optional.
     minLength: 1
-required: []