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
connman.PushMessage(&pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::BLOCK, *pblock));
            } else if (inv.IsMsgWitnessBlk()) {
                connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::BLOCK, *pblock));
            } else if (inv.IsMsgFilteredBlk()) {
                bool sendMerkleBlock = false;
                CMerkleBlock merkleBlock;
                if (pfrom.m_tx_relay != nullptr) {
                    LOCK(pfrom.m_tx_relay->cs_filter);
                    if (pfrom.m_tx_relay->pfilter) {
                        sendMerkleBlock = true;
                        merkleBlock = CMerkleBlock(*pblock, *pfrom.m_tx_relay->pfilter);
                    }
                }
                if (sendMerkleBlock) {
                    connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::MERKLEBLOCK, merkleBlock));
                    
                    
                    
                    
                    
                    
                    typedef std::pair<unsigned int, uint256> PairType;
                    for (PairType& pair : merkleBlock.vMatchedTxn)
                        connman.PushMessage(&pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::TX, *pblock->vtx[pair.first]));
                }
                
                    
            } else if (inv.IsMsgCmpctBlk()) {