Description of problem:

When running any of the pre-defined Metrics queries in OpenShift Developer Console, https://<cluster-url>/dev-monitoring/ns/project-X/metrics the user is reporting "no datapoing found".

For example when running the "CPU Usage" query which is running `sum(node_namespace_pod_container:container_cpu_usage_seconds_total:sum_rate{cluster="", namespace='<%= namespace %>'}) by (pod)` it will report back "no datapoint found".

When running the same in Prometheus we see all the data expected.

Once re-running the query in the Developer Console but removing `cluster=""` it also works there and shows the data as expected. Meaning the query like `sum(node_namespace_pod_container:container_cpu_usage_seconds_total:sum_rate{namespace='<%= namespace %>'}) by (pod)` works.

Version-Release number of selected component (if applicable):

 - OpenShift Container Platform 4.5.23 and 4.6.21

How reproducible:

 - N/A


Steps to Reproduce:
1. N/A

Actual results:

The user is seeing "no datapoints found" message but in fact the datapoints are there when removing `cluster=""` from the query.

Expected results:

The user should be able to see all data points without the need to modify the pre-defined queries.

Additional info:

The question is a bit, why the label `cluster=""` is set on most of the pre-defined queries as currently it does not appear to make sense to have it there. And why it could cause the Console to report back "no datapoints" even though there are datapoints available.