Resolve "Automatically set Prometheus step interval"

What does this MR do?

• Wait for !26228 (merged) (hence the WIP)

By computing the step interval passed to the query_range Prometheus API call we

1. improve the performance on the Prometheus server and GitLab by reducing the amount of data points sent back

2. prevent Prometheus from sending errors when requesting longer intervals

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26228#note_152622843

exceeded maximum resolution of 11,000 points per timeseries. Try decreasing the query resolution (?step=XX)

We target 600 data points for now but a step of at least 60s.

What are the relevant issue numbers?

#58839 (closed) #31368 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #58839 (closed)