Automatic merge from submit-queue
Remove implicit Prometheus metrics from client
**What this PR does / why we need it**: This PR starts to cut away at dependencies that the client has.
**Release note**:
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```release-note
The implicit registration of Prometheus metrics for request count and latency have been removed, and a plug-able interface was added. If you were using our client libraries in your own binaries and want these metrics, add the following to your imports in the main package: "k8s.io/pkg/client/metrics/prometheus".
```
cc: @kubernetes/sig-api-machinery @kubernetes/sig-instrumentation @fgrzadkowski @wojtek-t
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