`TestEventHandler` flakiness

## Failure

#### Link(s) to logs

- https://github.com/gravitational/teleport/actions/runs/16502543479/job/46664780636?pr=57138

#### Relevant snippet


```
--- FAIL: TestEventHandler (1.10s)
    --- FAIL: TestEventHandler/TestEvent (1.07s)
        testing.go:1232: TempDir RemoveAll cleanup: unlinkat /tmp/TestEventHandlerTestEvent4036776917/002/127.0.0.1_46107: directory not empty
```
