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

cmd/setup/river_queue_repeatable.go

@@ -16,7 +16,7 @@ func (mig *RiverMigrateRepeatable) Execute(ctx context.Context, _ eventstore.Eve
 	if mig.client.Type() != "postgres" {
 		return nil
 	}
-	return queue.New(mig.client).ExecuteMigrations(ctx)
+	return queue.NewMigrator(mig.client).Execute(ctx)
 }
 
 func (mig *RiverMigrateRepeatable) String() string {