Run subsystem-benchmark without network latency (#4068)

Implements the idea from
https://github.com/paritytech/polkadot-sdk/pull/3899
- Removed latencies
- Number of runs reduced from 50 to 5, according to local runs it's
quite enough
- Network message is always sent in a spawned task, even if latency is
zero. Without it, CPU time sometimes spikes.
- Removed the `testnet` profile because we probably don't need that
debug additions.

After the local tests I can't say that it brings a significant
improvement in the stability of the results. However, I belive it is
worth trying and looking at the results over time.