[9.1] [Synthetics] Fixed flaky test (#226367) (#226402)

# Backport

This will backport the following commits from `main` to `9.1`:
- [[Synthetics] Fixed flaky test
(#226367)](#226367)

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

### Questions ?
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<!--BACKPORT [{"author":{"name":"Francesco
Fagnani","email":"[email protected]"},"sourceCommit":{"committedDate":"2025-07-03T11:51:06Z","message":"[Synthetics]
Fixed flaky test (#226367)\n\nThis PR closes #221290 by fixing the flaky
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Fixed flaky
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Fixed flaky test (#226367)\n\nThis PR closes #221290 by fixing the flaky
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Fixed flaky test (#226367)\n\nThis PR closes #221290 by fixing the flaky
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Co-authored-by: Francesco Fagnani <[email protected]>

Author: kibanamachine

x-pack/solutions/observability/test/api_integration/apis/synthetics/sync_global_params.ts

@@ -33,9 +33,7 @@ export const LOCAL_LOCATION = {
 };
 
 export default function ({ getService }: FtrProviderContext) {
-  // FLAKY: https://github.com/elastic/kibana/issues/221290
-  // Failing: See https://github.com/elastic/kibana/issues/221290
-  describe.skip('SyncGlobalParams', function () {
+  describe('SyncGlobalParams', function () {
     this.tags('skipCloud');
     const supertestAPI = getService('supertest');
     const kServer = getService('kibanaServer');
@@ -138,6 +136,7 @@ export default function ({ getService }: FtrProviderContext) {
           [ConfigKey.MONITOR_QUERY_ID]: apiResponse.body.id,
           [ConfigKey.CONFIG_ID]: apiResponse.body.id,
           locations: [LOCAL_LOCATION, pvtLoc],
+          spaces: ['default'],
         })
       );
       newMonitorId = apiResponse.rawBody.id;
@@ -174,6 +173,13 @@ export default function ({ getService }: FtrProviderContext) {
         .set('kbn-xsrf', 'true')
         .send({ key: 'test', value: 'http://proxy.com' });
 
+      /*
+       * Creating a global parameter kicks off an asynchronous background task.
+       * We pause for 5 seconds to let that task finish before creating monitors that reference the param;
+       * if it’s still running when the monitor is added, Kibana would not schedule a second sync task.
+       */
+      await new Promise((resolve) => setTimeout(resolve, 5000));
+
       expect(apiResponse.status).eql(200);
     });
 
@@ -237,6 +243,7 @@ export default function ({ getService }: FtrProviderContext) {
           [ConfigKey.MONITOR_QUERY_ID]: apiResponse.body.id,
           [ConfigKey.CONFIG_ID]: apiResponse.body.id,
           locations: [LOCAL_LOCATION, pvtLoc],
+          spaces: ['default'],
         })
       );
       newHttpMonitorId = apiResponse.rawBody.id;