refactor(notification): use new queue package (#9360)

# Which Problems Are Solved

The recently introduced notification queue have potential race conditions.

# How the Problems Are Solved

Current code is refactored to use the queue package, which is safe in
regards of concurrency.

# Additional Changes

- the queue is included in startup
- improved code quality of queue

# Additional Context

- closes https://github.com/zitadel/zitadel/issues/9278

internal/notification/channels/channel.go

@@ -3,7 +3,7 @@ package channels
 import "github.com/zitadel/zitadel/internal/eventstore"
 
 type Message interface {
-	GetTriggeringEvent() eventstore.Event
+	GetTriggeringEventType() eventstore.EventType
 	GetContent() (string, error)
 }