This PR brings the fix
https://github.com/paritytech/substrate/pull/13396 to polkadot-sdk.

In the past, due to insufficient inbound slot count on polkadot &
kusama, this fix led to low peer count. The situation has improved since
then after changing the default ratio between `--in-peers` &
`--out-peers`.

Nevertheless, it's expected that the reported total peer count with this
fix is going to be lower than without it. This should be seen as the
correct number of working connections reported, as opposed to also
reporting already closed connections, and not as lower count of working
connections with peers.

This PR also removes the peer eviction mechanism, as closed substream
detection is a more granular way of detecting peers that stopped syncing
with us.

The burn-in has been already performed as part of testing these changes
in https://github.com/paritytech/polkadot-sdk/pull/3426.

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Co-authored-by: Aaro Altonen <a.altonen@hotmail.com>