chore(queue): use schema config instead of search_path and application_name to configure the database schema (#10075)

Removes manual schema and application name setup via raw SQL and
switches to using River’s built-in schema configuration.

# Which Problems Are Solved

River provides a configuration flag to set the schema of the queue.
Zitadel sets the schema through database statements which is not needed
anymore.

# How the Problems Are Solved

Set the schema in the river configuration and removed old code

internal/queue/database.go

@@ -1,45 +1,6 @@
 package queue
 
-import (
-	"context"
-	"sync"
-
-	"github.com/jackc/pgx/v5"
-
-	"github.com/zitadel/zitadel/internal/database/dialect"
-)
-
 const (
 	schema          = "queue"
 	applicationName = "zitadel_queue"
 )
-
-var conns = &sync.Map{}
-
-type queueKey struct{}
-
-func WithQueue(parent context.Context) context.Context {
-	return context.WithValue(parent, queueKey{}, struct{}{})
-}
-
-func init() {
-	dialect.RegisterBeforeAcquire(func(ctx context.Context, c *pgx.Conn) error {
-		if _, ok := ctx.Value(queueKey{}).(struct{}); !ok {
-			return nil
-		}
-		_, err := c.Exec(ctx, "SET search_path TO "+schema+"; SET application_name TO "+applicationName)
-		if err != nil {
-			return err
-		}
-		conns.Store(c, struct{}{})
-		return nil
-	})
-	dialect.RegisterAfterRelease(func(c *pgx.Conn) error {
-		_, ok := conns.LoadAndDelete(c)
-		if !ok {
-			return nil
-		}
-		_, err := c.Exec(context.Background(), "SET search_path TO DEFAULT; SET application_name TO "+dialect.DefaultAppName)
-		return err
-	})
-}