refactor(config): reduce references to config.GetInstance()

internal/acl/config.go

@@ -2,6 +2,7 @@ package acl
 
 import (
 	"net"
+	"sync/atomic"
 	"time"
 
 	"github.com/puzpuzpuz/xsync/v4"
@@ -39,6 +40,9 @@ type checkCache struct {
 	created time.Time
 }
 
+// could be nil
+var ActiveConfig atomic.Pointer[Config]
+
 const cacheTTL = 1 * time.Minute
 
 func (c *checkCache) Expired() bool {