CI test windows://python/ray/serve/tests:test_serve_with_tracing is consistently_failing

[aslonnie]

CI test windows://python/ray/serve/tests:test_serve_with_tracing is consistently_failing. Recent failures:
- https://buildkite.com/ray-project/postmerge/builds/15323#019ba6d7-72e5-4847-90f1-0fdae09f9626
- https://buildkite.com/ray-project/postmerge/builds/15323#019ba683-f553-4c19-88b6-9113580a5023

DataCaseName-windows://python/ray/serve/tests:test_serve_with_tracing-END
Managed by OSS Test Policy

[aslonnie]

This test is now considered as flaky because it has been failing on postmerge for too long. Flaky tests do not run on premerge.