[8.x] Unauthorized route migration for routes owned by stack-monitoring (#214787) (#214819)

# Backport

This will backport the following commits from `main` to `8.x`:
- [Unauthorized route migration for routes owned by stack-monitoring
(#214787)](https://github.com/elastic/kibana/pull/214787)

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

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

<!--BACKPORT [{"author":{"name":"Elena
Shostak","email":"165678770+elena-shostak@users.noreply.github.com"},"sourceCommit":{"committedDate":"2025-03-17T16:04:40Z","message":"Unauthorized
route migration for routes owned by stack-monitoring (#214787)\n\n##
Summary\n\nPassed security config to the core router, so it is correctly
captured.\n\n\n### Checklist\n\n- [x] The PR description includes the
appropriate Release Notes section,\nand the correct `release_note:*`
label is applied per
the\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)","sha":"e93a63331a8ea7c18d23b989418d54cf64adec7b","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["enhancement","Team:Monitoring","release_note:skip","Feature:Security/Authorization","backport:prev-minor","backport:version","Authz:
API migration","v9.1.0","v8.19.0"],"title":"Unauthorized route migration
for routes owned by
stack-monitoring","number":214787,"url":"https://github.com/elastic/kibana/pull/214787","mergeCommit":{"message":"Unauthorized
route migration for routes owned by stack-monitoring (#214787)\n\n##
Summary\n\nPassed security config to the core router, so it is correctly
captured.\n\n\n### Checklist\n\n- [x] The PR description includes the
appropriate Release Notes section,\nand the correct `release_note:*`
label is applied per
the\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)","sha":"e93a63331a8ea7c18d23b989418d54cf64adec7b"}},"sourceBranch":"main","suggestedTargetBranches":["8.x"],"targetPullRequestStates":[{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/214787","number":214787,"mergeCommit":{"message":"Unauthorized
route migration for routes owned by stack-monitoring (#214787)\n\n##
Summary\n\nPassed security config to the core router, so it is correctly
captured.\n\n\n### Checklist\n\n- [x] The PR description includes the
appropriate Release Notes section,\nand the correct `release_note:*`
label is applied per
the\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)","sha":"e93a63331a8ea7c18d23b989418d54cf64adec7b"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Elena Shostak <165678770+elena-shostak@users.noreply.github.com>

x-pack/platform/plugins/private/monitoring/server/plugin.ts

@@ -411,6 +411,7 @@ export class MonitoringPlugin
         const routeConfig = {
           path: options.path,
           validate: options.validate,
+          security: options.security,
         };
 
         if (method.toLowerCase() === 'post') {