test flake in pkg/cli/democluster: `TestTransientClusterSimulateLatencies`

[iliana]

https://github.com/oxidecomputer/cockroach/pull/60/checks?check_run_id=66862284254

https://buildomat.eng.oxide.computer/wg/0/details/01KKHVXH1G2DWRN5Z4MH0SVDKB/RaPStvpZCPsrRwBmAtq9CYdv0X6YtGXi9FjBTPzHjswMS9Bo/01KKHVYCA6J5XKEWSFNR9C7BAH#S2876

--- FAIL: TestTransientClusterSimulateLatencies (2.28s)
    test_log_scope.go:79: test logs captured to: /tmp/logTestTransientClusterSimulateLatencies1823489243
    test_log_scope.go:80: use -show-logs to present logs inline
    --- FAIL: TestTransientClusterSimulateLatencies/from_europe-west1 (0.07s)
        demo_cluster_test.go:246:
            	Error Trace:	/work/oxidecomputer/cockroach/pkg/cli/democluster/demo_cluster_test.go:246
            	Error:      	Should be true
            	Test:       	TestTransientClusterSimulateLatencies/from_europe-west1
            	Messages:   	expected duration at least 73ms, got 69.739171ms
    demo_cluster_test.go:255: -- test log scope end --