Improve dashboard performance / consider simplified top n calculation

[mamoep]

Is your feature request related to a problem? Please describe.
I have 22 clusters monitored and using the SVM dashboard takes up to 20 seconds before I get what I want. A high number of queries in variables for top n calculations.

Describe the solution you'd like
Consider calculating top n once based on volume iops & throughput and then use this value for all protocols.

Describe alternatives you've considered
n/a

Additional context
The approach would be different and my lead to less accurate results, but the usability would improve a lot. Top talkers on the cluster would still be visible.

[rahulguptajss]

Discord link.

[cgrinds]

Leaving open to capture remaining work. #2553 fixes SVM dashboard. We should roll this out to all dashboards with topk panels.

[cgrinds]

Nice job! I'll open a new issue for the few remaining vars that were not covered. See also #2599

[rahulguptajss]

verified in main