* Re-enable APM E2E tests and allow server to shut down cleanly on failure
Calling `process.exit` in the test script made it so the FTR runner would not properly shut down the server, and cause other tests to fail because Kibana was left running on a port. Remove that and just throw
instead.
No changes were made to the tests, as I was unable to reproduce any failures locally. I'll try in CI and see if we can get anything to fail.
Fixes#115280.
* Re-enable previously disabled APM E2E tests.
* Round to the nearest second in `getComparisonTypes` to avoid cases where a millisecond difference can change which results get shown.
* Simplify error count alert tests to test the "happy path" (#79284 exists in order to expand to more tests for rule editing and creation.)
* Wait for alert list API request to complete before clicking "Create rule" button when running the test to create a rule from the Stack Management UI.
I ran the e2e tests 100 times locally with no failures so I'm confident the flakiness has been addressed.
Fixes#114419.
Fixes#109205.
