Fix ingress/egress GCS dashboard by using `sum_over_time` aggregation
Description
This merge requests fixes our GCS ingress/egress dashboard by using sum_over_time
aggregation instead of simply multiplying this per-minute delta metric by 1440, as it looses accuracy when the multiplication is applied.
See this thread for more details: https://gitlab.com/gitlab-org/gitlab/-/issues/362897#note_964167108
Test dashboard: https://dashboards.gitlab.net/dashboard/snapshot/VF7w0Dm6hdcrF1y364LM6jkVUD0WGmdM?orgId=1&from=now-2d&to=now
/cc @stanhu
Edited by Grzegorz Bizon