flake: `TestAgent_Stats_SSH`

https://github.com/coder/coder/actions/runs/13827560334/job/38685219097 

```
    agent_test.go:99: 
        	Error Trace:	/Users/runner/work/coder/coder/agent/agent_test.go:99
        	Error:      	Condition never satisfied
        	Test:       	TestAgent_Stats_SSH/(:1)
        	Messages:   	never saw stats: <nil>
```