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
AssertLockHeld(::cs_main);
            uint64_t nCMPCTBLOCKVersion = (pfrom->GetLocalServices() & NODE_WITNESS) ? 2 : 1;
            if (lNodesAnnouncingHeaderAndIDs.size() >= 3) {
                
                
                connman.ForNode(lNodesAnnouncingHeaderAndIDs.front(), [&connman, nCMPCTBLOCKVersion](CNode* pnodeStop){
                    connman.PushMessage(pnodeStop, CNetMsgMaker(pnodeStop->GetCommonVersion()).Make(NetMsgType::SENDCMPCT, false, nCMPCTBLOCKVersion));
                    return true;
                });
                lNodesAnnouncingHeaderAndIDs.pop_front();
            }
            connman.PushMessage(pfrom, CNetMsgMaker(pfrom->GetCommonVersion()).Make(NetMsgType::SENDCMPCT, true, nCMPCTBLOCKVersion));
            lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
            return true;
        });
    }
}
static bool TipMayBeStale(const Consensus::Params &consensusParams) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    if (g_last_tip_update == 0) {
        g_last_tip_update = GetTime();
    }
    return g_last_tip_update < GetTime() - consensusParams.nPowTargetSpacing * 3 && mapBlocksInFlight.empty();
}
static bool CanDirectFetch(const Consensus::Params &consensusParams) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    return ::ChainActive().Tip()->GetBlockTime() > GetAdjustedTime() - consensusParams.nPowTargetSpacing * 20;
}
static bool PeerHasHeader(CNodeState *state, const CBlockIndex *pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main)