🐛 Informational message 'no more connections active and exiting' is logged as an error on graceful shutdown

**Describe the bug**
When gracefully shutting down the cloudflare agent, after all connections are closed. An error is written saying:
`no more connections active and exiting`
This is however expected behavior and should just be an informational message.

**To Reproduce**
1. Start the Cloudflare agent and make sure it gets connected to the cloudflare edge
2. Gracefully shut it down.

**Expected behavior**
The message is logged as informational message:
2022-09-22T14:16:56Z INF no more connections active and exiting

**Environment and versions**
- OS: Linux / docker
- Architecture: AMD
- Version: 2022.9.0

**Logs and errors**
2022-09-22T14:16:55Z INF Initiating graceful shutdown due to signal terminated ...
2022-09-22T14:16:56Z INF Unregistered tunnel connection connIndex=0
2022-09-22T14:16:56Z INF Unregistered tunnel connection connIndex=1
2022-09-22T14:16:56Z INF Unregistered tunnel connection connIndex=3
2022-09-22T14:16:56Z INF Unregistered tunnel connection connIndex=2
2022-09-22T14:16:56Z ERR no more connections active and exiting
2022-09-22T14:16:56Z INF Tunnel server stopped
2022-09-22T14:16:56Z INF Metrics server stopped

**Additional context**
The message is written here: https://github.com/cloudflare/cloudflared/blob/3d345d37487c8fe141ffbb473ef50cc46b46f491/supervisor/supervisor.go#L226