RPC metrics are intermixed

[xemul]

In the #2104 it was requested that (quoting)

The metrics are labeled with "domain" and "shard" values, each domain should have its own set of plots on the dashboard. Domains are dynamic.

However, current metrics do not implement that (see secreenshot of "RPC sent messages" plot, but other are also intermixed)

all domains are displayed on one plot making it impossible to analyze. My color blindness level is low enough for that screenshot already, e.g. "statement:$system:us-east 10.12.0.207" (the 2nd from the top) and "statement:default:us-east 10.12.2.37" (the 1st from the bottom) look the same to my eye. Same for two "yellow" lines on it. Neither it's possible to turn different domains displaying on or off

Monitoring version: