[Detection Engine][Test Fix] Ensure that alerts are absent before loading our alerts archive (#222691)

## Summary

This test has [failed a few times
recently](#219112) with a
`version_conflict_engine_exception`, stating explicitly that the
documents we're trying to load already exist in elasticsearch. In one
case the reason was obvious (the suite was retried), but in another it
was not clear why the data was there to cause this exception.

Regardless, adding this sanity check (deleting all the alerts) should
ensure that this behavior does not recur.

Closes #219112.


- [x] [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
- [x] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
([200x](https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/8329))
- [x] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

Author: rylnd

x-pack/test/security_solution_api_integration/test_suites/detections_response/detection_engine/alerts/trial_license_complete_tier/document_level_security.ts

@@ -9,6 +9,7 @@ import expect from '@kbn/expect';
 
 import { DETECTION_ENGINE_QUERY_SIGNALS_URL } from '@kbn/security-solution-plugin/common/constants';
 import { FtrProviderContext } from '../../../../../ftr_provider_context';
+import { deleteAllAlerts } from '../../../../../../common/utils/security_solution';
 
 const roleToAccessSecuritySolution = {
   name: 'sec_all_spaces',
@@ -73,6 +74,10 @@ export default ({ getService }: FtrProviderContext) => {
   const supertestWithoutAuth = getService('supertestWithoutAuth');
   const esArchiver = getService('esArchiver');
   const security = getService('security');
+  const supertest = getService('supertest');
+  const log = getService('log');
+  const es = getService('es');
+
   // Notes: Similar tests should be added for serverless once infrastructure
   // is in place to test roles in MKI enviornment.
   describe('@ess @skipInServerless find alert with/without doc level security', () => {
@@ -98,6 +103,7 @@ export default ({ getService }: FtrProviderContext) => {
         email: userAllSecWithDls.email,
       });
 
+      await deleteAllAlerts(supertest, log, es);
       await esArchiver.load(
         'x-pack/test/functional/es_archives/security_solution/alerts/8.8.0_multiple_docs',
         {