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.

polkadot/node/network/availability-recovery/benches/availability-recovery-regression-bench.rs

@@ -32,7 +32,7 @@ use polkadot_subsystem_bench::{
 };
 use std::io::Write;
 
-const BENCH_COUNT: usize = 50;
+const BENCH_COUNT: usize = 5;
 
 fn main() -> Result<(), String> {
 	let mut messages = vec![];
@@ -40,6 +40,8 @@ fn main() -> Result<(), String> {
 	let options = DataAvailabilityReadOptions { fetch_from_backers: true };
 	let mut config = TestConfiguration::default();
 	config.num_blocks = 3;
+	config.connectivity = 100;
+	config.latency = None;
 	config.generate_pov_sizes();
 
 	let state = TestState::new(&config);