[ML] Forecast api delete test: add retry to ensure forecast has time to complete before deletion (elastic#197111)

## Summary

Fixes elastic#195602

This PR adds a retry for 10 seconds to the deleteForecast utility
function to ensure the forecast has completed before a deletion attempt
is made.

Flaky test:
https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/7201


### Checklist

Delete any items that are not applicable to this PR.

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [ ] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [ ] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [ ] Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard accessibility](https://webaim.org/techniques/keyboard/))
- [ ] Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))
- [ ] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

Author: alvarezmelissa87

x-pack/test/api_integration/apis/ml/anomaly_detectors/forecast_with_spaces.ts

@@ -15,6 +15,7 @@ export default ({ getService }: FtrProviderContext) => {
   const supertest = getService('supertestWithoutAuth');
   const ml = getService('ml');
   const spacesService = getService('spaces');
+  const retry = getService('retry');
 
   const forecastJobId = 'fq_single_forecast';
   const forecastJobDatafeedId = `datafeed-${forecastJobId}`;
@@ -45,21 +46,22 @@ export default ({ getService }: FtrProviderContext) => {
     user: USER,
     expectedStatusCode: number
   ) {
-    const { body, status } = await supertest
-      .delete(
-        `${
-          space ? `/s/${space}` : ''
-        }/internal/ml/anomaly_detectors/${jobId}/_forecast/${forecastId}`
-      )
-      .auth(user, ml.securityCommon.getPasswordForUser(user))
-      .set(getCommonRequestHeader('1'));
-    ml.api.assertResponseStatusCode(expectedStatusCode, status, body);
-
-    return body;
+    await retry.tryForTime(10000, async () => {
+      const { body, status } = await supertest
+        .delete(
+          `${
+            space ? `/s/${space}` : ''
+          }/internal/ml/anomaly_detectors/${jobId}/_forecast/${forecastId}`
+        )
+        .auth(user, ml.securityCommon.getPasswordForUser(user))
+        .set(getCommonRequestHeader('1'));
+      ml.api.assertResponseStatusCode(expectedStatusCode, status, body);
+
+      return body;
+    });
   }
 
-  // Failing see: https://github.com/elastic/kibana/issues/195602
-  describe.skip('POST anomaly_detectors _forecast with spaces', function () {
+  describe('POST anomaly_detectors _forecast with spaces', function () {
     let forecastId: string;
     before(async () => {
       await esArchiver.loadIfNeeded('x-pack/test/functional/es_archives/ml/farequote');
@@ -110,11 +112,11 @@ export default ({ getService }: FtrProviderContext) => {
     });
 
     it('should not delete forecast for user without permissions', async () => {
-      await await deleteForecast(forecastJobId, forecastId, idSpace1, USER.ML_VIEWER, 403);
+      await deleteForecast(forecastJobId, forecastId, idSpace1, USER.ML_VIEWER, 403);
     });
 
     it('should delete forecast for user with permissions', async () => {
-      await await deleteForecast(forecastJobId, forecastId, idSpace1, USER.ML_POWERUSER, 200);
+      await deleteForecast(forecastJobId, forecastId, idSpace1, USER.ML_POWERUSER, 200);
     });
 
     it('should not run forecast for open job with invalid duration', async () => {