Automatic merge from submit-queue
Use Prometheus instrumentation conventions
The `System` and `Subsystem` parameters are subject to removal.
(x-ref: https://github.com/prometheus/client_golang/issues/240)
All metrics should use base units, which is seconds in the duration
case.
Counters should always end in `_total` and metrics should avoid
referring to potential label dimensions. Those should rather be
mentioned in the documentation string.
@kubernetes/sig-instrumentation
Reference docs:
https://prometheus.io/docs/practices/instrumentation/https://prometheus.io/docs/practices/naming/
**Release note**:
```
Breaking change: Renamed REST client Prometheus metrics to follow the instrumentation conventions ("request_latency_microseconds" -> "rest_client_request_latency_seconds", "request_status_codes" -> "rest_client_requests_total"). Please update your alerting pipeline if you rely on them.
```
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