text: Title: [Task Manager] Clean up performance tests
  Body: With https://github.com/elastic/kibana/pull/117294, we are removing the `perf_hooks` in task manager due to possible memory leakage.  There is also a set of skipped functional tests in https://github.com/elastic/kibana/blob/main/x-pack/test/plugin_api_perf/test_suites/task_manager/index.ts that we should make sure to remove once we've confirmed that 🤞 removing the perf_hooks fixes the memory issue.