Currently, the logic around whether we called `CAddrMan::Connected()` for
a peer is spread between verack processing (where we discard inbound
peers) and `FinalizeNode` (where we discard misbehaving and
block-relay-only peers). Consolidate that logic to a single place.
Also remove the `CNode.fCurrentlyConnected` bool, which is now
redundant. We can rely on `CNode.fSuccessfullyConnected`, since the two
bools were only ever flipped to true in the same place.
This is a backport of core#20291 [1/2]
https://github.com/bitcoin/bitcoin/pull/20291/commits/eefe19471868ef0cdc9d32473d0b57015e7647eei
Depends on D10697