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/queue/migrate.go

@@ -0,0 +1,38 @@
+package queue
+
+import (
+	"context"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/riverqueue/river/riverdriver"
+	"github.com/riverqueue/river/riverdriver/riverpgxv5"
+	"github.com/riverqueue/river/rivermigrate"
+
+	"github.com/zitadel/zitadel/internal/database"
+)
+
+type Migrator struct {
+	driver riverdriver.Driver[pgx.Tx]
+}
+
+func NewMigrator(client *database.DB) *Migrator {
+	return &Migrator{
+		driver: riverpgxv5.New(client.Pool),
+	}
+}
+
+func (m *Migrator) Execute(ctx context.Context) error {
+	_, err := m.driver.GetExecutor().Exec(ctx, "CREATE SCHEMA IF NOT EXISTS "+schema)
+	if err != nil {
+		return err
+	}
+
+	migrator, err := rivermigrate.New(m.driver, nil)
+	if err != nil {
+		return err
+	}
+	ctx = WithQueue(ctx)
+	_, err = migrator.Migrate(ctx, rivermigrate.DirectionUp, nil)
+	return err
+
+}