subsystem-bench: adjust test config to Kusama (#3583)

Fixes https://github.com/paritytech/polkadot-sdk/issues/3528

```rust
latency:
    mean_latency_ms = 30 // common sense
    std_dev = 2.0 // common sense
n_validators = 300 // max number of validators, from chain config
n_cores = 60 // 300/5
max_validators_per_core = 5 // default
min_pov_size = 5120 // max
max_pov_size = 5120 // max
peer_bandwidth = 44040192 // from the Parity's kusama validators
bandwidth = 44040192 // from the Parity's kusama validators
connectivity = 90 // we need to be connected to 90-95% of peers
```