Exposes endpoint at /metrics for Grafana / Prometheus to slobber from.
See the collected stats at /metrics
{__name__=~"ep_performance_test_hooks_loadTimes__(.*)_fetchUntilResponseEndTime"}
{__name__=~"ep_performance_test_hooks_loadTimes__(.*)_fetchUntilResponseEndTime"}
ep_performance_test_hooks_etherpadHooksDuration_postAceInit
totalUsers
(memoryUsageHeap / 1024 / 1024)