logger: Avoid slow calls in http logger Send() function (#17747)

Send() is synchronous and can affect the latency of S3 requests when the
logger buffer is full.

Avoid checking if the HTTP target is online or not and increase the
workers anyway since the buffer is already full.

Also, avoid logs flooding when the audit target is down.

internal/logger/audit.go

@@ -28,7 +28,6 @@ import (
 	"github.com/minio/minio/internal/mcontext"
 	"github.com/minio/pkg/logger/message/audit"
 
-	"github.com/minio/madmin-go/v3"
 	xhttp "github.com/minio/minio/internal/http"
 )
 
@@ -145,7 +144,7 @@ func AuditLog(ctx context.Context, w http.ResponseWriter, r *http.Request, reqCl
 	// Send audit logs only to http targets.
 	for _, t := range auditTgts {
 		if err := t.Send(ctx, entry); err != nil {
-			LogAlwaysIf(context.Background(), fmt.Errorf("event(%v) was not sent to Audit target (%v): %v", entry, t, err), madmin.LogKindAll)
+			LogOnceIf(ctx, fmt.Errorf("Unable to send an audit event to the target `%v`: %v", t, err), "send-audit-event-failure")
 		}
 	}
 }