multi: wire up gossip filter concurrency config

In this commit, we complete the integration of the configurable gossip
filter concurrency by wiring the new FilterConcurrency configuration
through all layers of the application.

The changes connect the gossip.filter-concurrency configuration option
from the command-line interface through the server initialization code
to the gossiper and sync manager. This ensures that operators can
actually use the new configuration option to tune their node's
concurrent gossip filter processing capacity based on their specific
requirements and available resources.

config.go

@@ -719,6 +719,7 @@ func DefaultConfig() Config {
 			AnnouncementConf:      discovery.DefaultProofMatureDelta,
 			MsgRateBytes:          discovery.DefaultMsgBytesPerSecond,
 			MsgBurstBytes:         discovery.DefaultMsgBytesBurst,
+			FilterConcurrency:     discovery.DefaultFilterConcurrency,
 		},
 		Invoices: &lncfg.Invoices{
 			HoldExpiryDelta: lncfg.DefaultHoldInvoiceExpiryDelta,

server.go

@@ -1225,6 +1225,7 @@ func newServer(ctx context.Context, cfg *Config, listenAddrs []net.Addr,
 		AssumeChannelValid:      cfg.Routing.AssumeChannelValid,
 		MsgRateBytes:            cfg.Gossip.MsgRateBytes,
 		MsgBurstBytes:           cfg.Gossip.MsgBurstBytes,
+		FilterConcurrency:       cfg.Gossip.FilterConcurrency,
 	}, nodeKeyDesc)
 
 	accessCfg := &accessManConfig{