Improve overall visualization of diffs usage and performance by adding graphs to Grafana
As of &15 (closed), we've been focusing on improving the ability of viewing large diffs files on GitLab.
But in order to improve the current limits and see the actual impact of that, we need proper graphs with more data. Ideally we should be able to see:
- Throughput of diffs serving (how many diffs we serve per hour for instance?)
- Timeout counts
These should count for all diff-related views compare, merge request and commit diffs.
Ideally we should also have https://gitlab.com/gitlab-com/infrastructure/issues/3499 fixed in order to see .json
endpoints timings correctly.