scylla-detailed: compression panels, remove raw and make the title clearer

[amnonh]

After the change, add ratio, and show only sent information

Fixes #2392

[amnonh]

@michoecho following comment from @mykaul do we need both send and receive? It should be the same, so maybe we can show just one of them

[michoecho]

@michoecho following comment from @mykaul do we need both send and receive? It should be the same, so maybe we can show just one of them

The contents of the dashboard should be dictated by its purpose.

If the purpose is to show the compression ratio, or the overall throughput of RPC network traffic in the cluster, then showing "send" alone is good enough, because "receive" should — in total — have the same information.
If the purpose is to be yet another data point for debugging performance issues, then send and receive are different, and should be both displayed.

[mykaul]

@michoecho following comment from @mykaul do we need both send and receive? It should be the same, so maybe we can show just one of them

The contents of the dashboard should be dictated by its purpose.

If the purpose is to show the compression ratio, or the overall throughput of RPC network traffic in the cluster, then showing "send" alone is good enough, because "receive" should — in total — have the same information. If the purpose is to be yet another data point for debugging performance issues, then send and receive are different, and should be both displayed.

For debugging we have the Prometheus interface, if we need to query both, IMHO.