loadbot: Blocking channel.

[JoeGruffins]

Since #3123 am seeing this when starting:

2025-03-13 16:22:14.884 [ERR] CORE:STACKER:0: blocking notification channel
2025-03-13 16:22:14.885 [ERR] CORE:STACKER:0: blocking notification channel
2025-03-13 16:22:14.887 [ERR] CORE:STACKER:0: blocking notification channel
2025-03-13 16:22:14.889 [ERR] CORE:STACKER:0: blocking notification channel
2025-03-13 16:22:14.890 [ERR] CORE:STACKER:0: blocking notification channel
2025-03-13 16:22:14.891 [ERR] CORE:STACKER:0: blocking notification channel
2025-03-13 16:22:14.892 [ERR] CORE:STACKER:0: blocking notification channel

[JoeGruffins]

It's because of the sleeps I added to wait for a block but I don't understand why that is blocking the notification channel atm.