AFAICT, as of commit a0a422c,  we have 2 different logics to evict outbound peers : lagging-chain (`ConsiderEviction`) and (`CheckForStaleTipAndEvictPeers`). The former to sanitize out lazy/buggy peers who have never sent us a valid header and are always staying behind our tip, the latter triggered in case of stale tip due to block variance to seek a better chain by rotating our outbound peers if we already reach an outbound limit (`EvictExtraOutboundPeers`).

Block-relay-only peers were introduced by #15719. Contrary to outbound full-relay peers who provided us at least a useful header, they're not protected by lagging-chain eviction.

We actually have a comment inside `ProcessHeadersMessage` indicating the contrary behavior. We should either document cleanly that block-relay-only aren't protected or effectively extend the scope of protection to them.

Hinted during #19724 review, see https://github.com/bitcoin/bitcoin/pull/19724#discussion_r475144532
pfrom.GetId(), (fLogIPs ? strprintf(", peeraddr=%s", pfrom.addr.ToString()) : ""),
                      pfrom.m_tx_relay == nullptr ? "block-relay" : "full-relay");
        }
        if (pfrom.GetCommonVersion() >= SENDHEADERS_VERSION) {
            
            
            
            
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::SENDHEADERS));
        }
        if (pfrom.GetCommonVersion() >= SHORT_IDS_BLOCKS_VERSION) {
            
            
            
            
            
            bool fAnnounceUsingCMPCTBLOCK = false;
            uint64_t nCMPCTBLOCKVersion = 2;
            if (pfrom.GetLocalServices() & NODE_WITNESS)
                m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
            nCMPCTBLOCKVersion = 1;
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
        }
        pfrom.fSuccessfullyConnected = true;
        return;
    }
    
    
    if (msg_type == NetMsgType::WTXIDRELAY) {
        if (pfrom.fSuccessfullyConnected) {