Remove status from http_request_duration_seconds

What does this MR do?

This removes the status label from the http_request_duration_seconds histogram. For error rates, we've moved the status label to the http_requests_total counter.

We've added the status label to the http_requests_total in !44468 (merged)

Then we switched to using that for our dashboards and alerts in gitlab-com/runbooks!2841 (merged)

This is the last step for gitlab-com/gl-infra/scalability#585 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done