Remove duplicated connection limits checks (#6156)

* move main Behaviour to mod.rs for better readibility

and remove connection limits checks after connection has been established,

as those checks have already been done by connection limits Behaviour.

* improve logging wording wrt dial logic

when we call dial_peer we are not yet dialing but just adding the peer to the dial queue

* do not use a constant for MAX_CONNECTIONS_PER_PEER

we only use it at one place, and the function call is explicit.

* address review and re-instate connection limits checks,

but do it before the connection has been established.

* Merge branch 'unstable' of github.com:sigp/lighthouse into remove-dial-error-denied

* Merge branch 'unstable' of github.com:sigp/lighthouse into remove-dial-error-denied

beacon_node/lighthouse_network/src/service/utils.rs

@@ -24,8 +24,6 @@ use types::{
 };
 
 pub const NETWORK_KEY_FILENAME: &str = "key";
-/// The maximum simultaneous libp2p connections per peer.
-pub const MAX_CONNECTIONS_PER_PEER: u32 = 1;
 /// The filename to store our local metadata.
 pub const METADATA_FILENAME: &str = "metadata";