Fix farming cluster forwarders and identification intervals

[nazar-pc]

This fixes two issues:

• Duration::MAX support in last tokio release wasn't fixed fully, which this PR avoids in the first place
• Broadcasts are avoided in all threads except one after Multithreaded farming cluster services #2849 to avoid extra load and unnecessary message duplication (like the same reward being signed tens of times)

I also removed multi-threading from plotter. While nice for consistency, it was useless in that context.

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