[Discover] [Rule Form v2] Search source alert tests depend on Stack Management application

[Zacqary]

Changes to the rule creation flow in Stack Management broke Discover tests related to the search source alert. This PR affected only the UI for Stack Management and Observability, but ultimately triggered codeowner review from Discover because of this test dependency.

In x-pack/test/functional_with_es_ssl/apps/discover_ml_uptime/discover/search_source_alert.ts (and its test_serverless equivalent), there are several places where this line of code is called:

await PageObjects.common.navigateToApp('management');

The tests appear to be doing this to create a rule, which then gets evaluated.

It's not sustainable for Discover tests to be dependent on a different application, especially with the work we're doing on Rule Flow V2. This test will likely break again in the future for changes unrelated to Discover. Therefore, we need to keep this test in the Discover app entirely, or to have it create rules through API calls.

[elasticmachine]

Pinging @elastic/kibana-data-discovery (Team:DataDiscovery)

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)