I receive closed warning when it disabled in telegram plugin

[demshin]

Issue Summary
Hi
I'm using telegram plugin with TELEGRAM_DISABLE_NOTIFICATION_SEVERITY which disable notifications for warnings. Than I don't receive warnings but I receive closed warnings. What do I need to not receive closed warnings?

Environment

• OS: centos 7

• API version: 8.5.0

• Deployment: self-hosted in k8s

• For self-hosted, WSGI environment: nginx

• Database: Postgres

• Server config:
  Auth enabled? Yes
  Auth provider? Basic
  Customer views? No

• web UI version: 8.5.0

To Reproduce
Steps to reproduce the behavior:

1. Receive alert with severity warning from prometheus alertmanager.
2. It is showing in interface.
3. I don't receive message ti telegram. That's right!
4. Than warning alert closed.
5. I receive message in telegram. But I don't want.

Expected behavior
I don't receive warning in telegram.