[Internal Observability] Re-enable event stats again. (#21515)
[Internal Observability] Re-enable event stats again. (#21515)

I tried reproducing the many pg mini integration failure from this PR; https://github.com/ray-project/ray/pull/21216, but I failed to do that. (this was the only test that became flaky when we turned on the flag last time).

I tried
- Run tests:test_placement_group_mini_integration 5 times instead of 3 (the default)
- Re-run the PR 3 times.

So I think it is worth trying re-enabling it again. 

ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray,ray-project/ray